wrangler check startup now reports your Worker's raw and compressed bundle sizes. It also summarizes local CPU activity during startup directly in your terminal.
Large bundles and costly startup work can introduce cold-start latency, so use this command to find code and large dependencies that slow your Worker before it handles requests.
The summary includes sampled, active, garbage collection, and idle time. Wrangler continues to save a .cpuprofile file for detailed flamegraph analysis in Chrome DevTools or VS Code.
⛅️ wrangler 4.116.0───────────────────────────────────────────────├ Building your Worker│ Worker Built! 🎉│├ Analysing│ Startup phase analysed││ Bundle: 7171.25 KiB / gzip: 2197.00 KiB││ Local startup profile:│ Profile window: 70.3 ms│ Sampled time: 70.3 ms│ Active: 38.5 ms (including 3.7 ms garbage collection)│ Idle: 31.8 ms│ Samples: 36││ CPU Profile has been written to worker-startup.cpuprofile. Load it into the Chrome DevTools profiler (or directly in VSCode) to view a flamegraph.││ Note that the CPU Profile was measured on your Worker running locally on your machine, which has a different CPU than when your Worker runs on Cloudflare.││ As such, CPU Profile can be used to understand where time is spent at startup, but the overall startup time in the profile should not be expected to exactly match what your Worker's startup time will be when deploying to Cloudflare.
The profile runs locally, so its duration will differ from startup time on Cloudflare. For authoritative startup time, deploy your Worker or upload a version.
Available in Wrangler version 4.116.0 or later. For more information, refer to wrangler check startup.
MCP server portals now support four Code Mode policies: Off, Opt-in, On by default, and Enforced. Admins can choose whether Code Mode is unavailable, optional, enabled by default, or required for every session.
Existing portals retain their current behavior. Portals that previously allowed Code Mode use Opt-in, while portals that did not allow Code Mode use Off. New portals also use Opt-in by default.
Clients turn on Code Mode for an Opt-in portal with ?codemode=search_and_execute. The On by default policy lets clients opt out with ?codemode=off, which avoids nested code execution when a client runs its own Code Mode implementation. The Off and Enforced policies ignore client overrides.
The Cloudflare API exposes these policies through the code_mode field:
{ "code_mode": "default_on"}
The supported values are off, opt_in, default_on, and enforced. The previous allow_code_mode boolean is deprecated.
For configuration details and client behavior, refer to Code Mode policies.
You can now use AI Search directly from popular agent frameworks, adding grounded retrieval to an existing app instead of calling the REST API by hand. The new Agents section has guides for the Vercel AI SDK, LangChain, and the Cloudflare Agents SDK. The AI SDK integration is a new package, and the LangChain integration is a new retriever in the existing langchain-cloudflare package.
Vercel AI SDK
The ai-search-provider ↗ package connects AI Search to the AI SDK, and targets AI SDK v6 (ai@^6). Pass instance.chat() to generateText or streamText to generate a response grounded in your indexed content, with the retrieved chunks returned as sources. You can also expose instance.search() as a tool for agent loops.
The langchain-cloudflare package (PyPI ↗, GitHub ↗) provides CloudflareAISearchRetriever, a standard LangChain retriever backed by AI Search. Use it on its own, wrap it with create_retriever_tool to give an agent a search tool, or drop it into a RAG chain. It works with REST credentials or a Worker binding inside a Python Worker.
from langchain_cloudflare import CloudflareAISearchRetrieverretriever = CloudflareAISearchRetriever( account_id=ACCOUNT_ID, api_token=API_TOKEN, instance_name="knowledge-base", retrieval_type="hybrid",)docs = retriever.invoke("How do I configure Workers AI?")
Cloudflare Agents SDK
The Cloudflare Agents SDK could already reach AI Search through the Workers binding. The new guide walks through building a stateful chat agent that provisions its own instance, indexes content, and searches it from a tool.
import { tool } from "ai";import { z } from "zod";const instance = env.AI_SEARCH.get("knowledge-base");// Expose AI Search to the agent's model as a tool it can call.const searchKnowledgeBase = tool({ description: "Search the knowledge base for relevant content.", inputSchema: z.object({ query: z.string() }), execute: ({ query }) => instance.search({ query }),});
import { tool } from "ai";import { z } from "zod";const instance = env.AI_SEARCH.get("knowledge-base");// Expose AI Search to the agent's model as a tool it can call.const searchKnowledgeBase = tool({ description: "Search the knowledge base for relevant content.", inputSchema: z.object({ query: z.string() }), execute: ({ query }) => instance.search({ query }),});
For the full walkthroughs, including creating an instance and indexing content, refer to the Agents guides.
Workers Builds now uses Node.js 24.18.0 by default. The build image preinstalls Node.js 22.23.2 and 24.18.0.
You can continue to override the default with the NODE_VERSION environment variable, an .nvmrc file, or a .node-version file. For more information, refer to Override default versions.
This release introduces new rules and updates existing threat signatures to provide targeted protections for vulnerabilities in Nuxt Server Island components and Alibaba Fastjson deserialization routines, alongside enhanced protections for cloud metadata Server-Side Request Forgery (SSRF) and obfuscated command injection attempts.
Key Findings
Nuxt Server Island - RCE(GHSA-9473-5f9j-94wq): An unauthenticated vulnerability in Nuxt Server Islands where remote attackers can supply arbitrary component names or props to endpoints. Manipulating these parameters allows unauthenticated component Remote Code Execution (RCE) on the server.
Alibaba Fastjson JSONType Remote Code Execution: A unauthenticated remote code execution vulnerability in Alibaba Fastjson (≤ 1.2.83) during JSON deserialization. Under default configurations, attackers can execute arbitrary system commands, bypassing traditional classpath and gadget-based defenses.
Generic Protections (SSRF & Command Injection): Added improved detection logic targeting Server-Side Request Forgery (SSRF) in cloud-hosted applications, alongside new rules targeting obfuscated command injection patterns across request parameters.
Ruleset
Rule ID
Legacy Rule ID
Description
Previous Action
New Action
Comments
Cloudflare Managed Ruleset
N/A
SSRF - Cloud - Beta
Log
Block
This is an improved detection.
Cloudflare Managed Ruleset
N/A
Command Injection - Obfuscation
Log
Block
This is a new detection.
Cloudflare Managed Ruleset
N/A
Alibaba Fastjson JSONType Remote Code Execution - Body
Log
Block
This is a new detection.
Cloudflare Managed Ruleset
N/A
Nuxt Server Island - RCE
N/A
Block
This is a new detection.This was labeled as Generic Rules - RCE.
Cloudflare is rolling out updated formatting for the data field in the 1.1.1.1 DoH JSON API (application/dns-json). During the roll out responses may use either the old or new format.
Human-readable display for additional record types
Several record types previously returned their data field in RFC 3597 ↗ generic hex encoding (\# <length> <hex>). These now use standard presentation format:
DNSSEC-related records now use numeric algorithm identifiers as defined in RFC 4034 ↗ instead of mnemonic names. This affects RRSIG, DS, CDS, DNSKEY, and CDNSKEY records. For example, RSASHA256 becomes 8, ECDSAP256SHA256 becomes 13, and ED25519 becomes 15. DS digest types also change from mnemonic to numeric: SHA-256 becomes 2.
Cloudflare's product-specific MCP servers now support the new MCP 2026-07-28 Specification. Each request runs on a fresh stateless server without an MCP protocol session or protocol-specific Durable Object.
The /mcp endpoint also accepts stateless requests from 2025 Streamable HTTP clients. Most clients can reconnect without configuration changes.
Use /mcp for new connections. Historical /sse URLs continue to work as aliases for the same Streamable HTTP handler, but they no longer serve the deprecated HTTP+SSE transport. If a client forces SSE transport, change it to Streamable HTTP or automatic transport detection.
Browser Run now supports structured handoff for Human in the Loop workflows. Using Cloudflare-specific CDP commands, your agent can signal that it needs help, a human steps in through Live View to handle the task, and the agent resumes once the work is done.
For agents running multi-step browser workflows, a single login wall or unexpected prompt can fail the entire run. Previously, scripts had to manage human intervention manually by sharing a Live View URL and polling for completion. Structured handoff replaces this with a formal pause-and-resume flow.
The following example requests human intervention for a login page and waits for the human to finish before continuing:
const cdp = await page.createCDPSession();// Get Live View URL for the human operatorconst { devtoolsFrontendUrl } = await cdp.send("Cloudflare.getLiveView", { mode: "tab",});console.log(`Human input needed: ${devtoolsFrontendUrl}`);// Request human intervention and wait for completionconst handoffComplete = new Promise((resolve) => { cdp.once("Cloudflare.handoffComplete", resolve);});await cdp.send("Cloudflare.handoff", { instructions: "Please log in with your credentials", timeout: 600000,});const result = await handoffComplete;console.log(result.success ? "Handoff complete" : `Failed: ${result.reason}`);
You can now set a maximum time-to-live (TTL) for DNS responses returned by Gateway. When an upstream DNS record has a TTL that exceeds the configured maximum, Gateway caps it to your specified value. This ensures that DNS policy changes - such as blocking a newly identified malicious domain - take effect faster across all clients.
The setting is available at two levels:
Account level - In Traffic Policies > Traffic Settings, under Proxy and inspection. This sets the default cap for all DNS locations.
Per-location - Each DNS location can inherit the account setting, disable the cap, or override it with a custom value.
Two new fields are also available in DNS logs: upstream_record_ttls (the original TTL from the upstream response) and applied_max_ttl (the cap Gateway applied). These appear in the DNS logs column picker and in Logpush datasets.
We are limiting Workers Free plan access to a few resource-intensive models so we can prioritize capacity for the broader Workers AI user base. This helps everyone get a more reliable inference experience, with fewer 429 and 3040 (Out of Capacity) errors.
On the Workers Free plan, requests to these models now return a 403 HTTP error (internal error 5035) prompting you to upgrade. The Workers Paid plan starts at $5 per month and still includes the 10,000 free Neurons per day allocation, with usage beyond that billed at each model's pricing.
Many models remain available on the Workers Free plan, including:
The Workers runtime now provides built-in tracing.startActiveSpan() and span.end() APIs, allowing you to write custom spans for operations that last beyond a single callback — for example, instrumenting a stream pipeline where the span should stay open until the stream is fully consumed.
This augments the existing API for writing custom spans, tracing.enterSpan(), which automatically ends a span when its callback is returned. With startActiveSpan(), the span remains open after the callback returns, and you call span.end() when the work is complete:
src/index.jsjs
import { tracing } from "cloudflare:workers";const encoder = new TextEncoder();export default { fetch() { return tracing.startActiveSpan("stream-response", (span) => { let timer; const body = new ReadableStream({ start(controller) { controller.enqueue(encoder.encode("Starting...\n")); timer = setTimeout(() => { controller.enqueue(encoder.encode("Complete.\n")); controller.close(); span.setAttribute("stream.status", "complete"); span.end(); }, 1000); }, cancel() { if (timer !== undefined) clearTimeout(timer); span.setAttribute("stream.status", "cancelled"); span.end(); }, }); return new Response(body, { headers: { "content-type": "text/plain" }, }); }); },};
Agents SDK v0.20.0 adds client and server support for the MCP 2026-07-28 release candidate ↗. Workers can serve tools, prompts, resources, and elicitation without an MCP transport session or Durable Object. Agents can connect to both MCP 2026-07-28 servers and existing legacy servers.
Client support
The MCP client manager now uses @modelcontextprotocol/client. For each connection, it probes for MCP 2026-07-28 support with server/discover. If the server does not support the stateless protocol, the client continues with the legacy initialize handshake on the same connection. Existing addMcpServer calls do not need a protocol-version setting or separate clients for each protocol generation.
For stateless requests, elicitation uses input_required through multi-round-trip requests (MRTR). The legacy path uses the same form and URL handlers for pushed requests. The SDK collects input, retries the original operation, and resolves the original callTool, getPrompt, or readResource promise with its final result.
OAuth callbacks now validate issuer metadata through the v2 SDK. Discovery state and issuer-bound credentials persist across browser redirects and Durable Object hibernation.
Run stateless servers
createMcpHandler now accepts a factory that returns a server from @modelcontextprotocol/server. The factory creates an isolated server for each request.
The isolated agents/mcp/server entry keeps McpAgent, WorkerTransport, MCP client transports, and SDK v1 modules out of stateless server bundles.
The Workers wrapper validates present browser Origins, supports explicit delegation to trusted Origin middleware, and exposes request handling plus typed change notifications.
Backward compatibility
The same createMcpHandler(createServer)(request, env, ctx) route serves MCP 2026-07-28 clients and legacy clients that use stateless requests. You do not need separate routes or tool definitions for ordinary tools, prompts, and resources.
McpAgent is deprecated and feature-frozen. Migrate existing McpAgent servers to the stateless handler at your earliest convenience. If a server depends on protocol sessions, RPC, pushed server-to-client requests, standalone streams, or replay, use the migration guide to design stateless equivalents and run both routes while clients transition.
Migrate existing SDK v1 servers
Upgrade the Agents SDK:
npm i agents@latest
yarn add agents@latest
pnpm add agents@latest
bun add agents@latest
Move ordinary SDK v1 server definitions into an SDK v2 factory and serve them with createMcpHandler. The handler's default legacy compatibility means most stateless deployments need only one route.
If an existing McpAgent server still needs sessionful features, add the stateless path beside it. Use isLegacyRequest() to send only legacy traffic to the existing route:
Migrate the remaining sessionful features, allow existing sessions to drain, then remove the legacy route. Refer to Migrate to MCP SDK v2 for package changes, compatibility limits, and rollout steps.
Deprecations in v0.20.0
This release deprecates the following Agents SDK APIs:
Deprecated API
Replacement
Status
McpAgent
Use an SDK v2 factory with createMcpHandler for stateless servers. Use the migration guide to replace stateful features before removing a legacy route.
Feature-frozen. No removal version is announced.
createMcpHandler(v1Server, options)
Move the server to an SDK v2 factory and call createMcpHandler(factory, options). Use createLegacyMcpHandler only as a temporary bridge for sessionful features.
Scheduled for removal in the next major version.
MCPClientManager.callTool(params, resultSchema, options) and the equivalent withX402Client overload
Use callTool(params, options) or callTool(confirm, params, options).
Compatibility overload. No removal version is announced.
The MCP 2026-07-28 draft separately deprecates Roots, Sampling, Logging, the old HTTP+SSE transport, and Dynamic Client Registration.
Audit Logs v2 now includes Resource History. For any audit log entry, you can see the sequence of previous changes to the same resource and view a side-by-side diff of what was modified.
Resource History uses the audit log entries you already have. There is no additional configuration, no backend recapture, and no changes to how audit logs are generated.
Dashboard:
Go to Manage Account > Audit Logs.
Open any audit log entry.
Select the History tab to see the full history for that resource.
Select any earlier entry to see a side-by-side diff of the fields that changed between it and the current entry.
API:
Use the History endpoint to retrieve the change history for any audit log entry:
GET https://api.cloudflare.com/client/v4/accounts/{account_id}/logs/audit/{id}/history
The endpoint is also available for organization-scoped audit logs at /organizations/{organization_id}/logs/audit/{id}/history.
Wrangler now provides createTestHarness(), an API for running integration tests against Workers built with Wrangler or the Cloudflare Vite plugin from any Node.js test runner.
Sippy can now incrementally migrate data from Azure Blob Storage and any S3-compatible object storage provider to Cloudflare R2, in addition to Amazon S3 and Google Cloud Storage. Sippy copies objects to R2 as your application requests them, so you can start serving data from R2 without first moving your entire dataset or paying migration-specific egress fees.
Enable Sippy
Run the following command and follow the prompts to select and configure your source storage provider:
npx wrangler r2 bucket sippy enable <BUCKET_NAME>
For Azure Blob Storage, provide your storage account name, container name, and either an account key or a shared access signature (SAS) token with read and list permissions. For an S3-compatible provider, provide the S3 API endpoint URL and read-only Access Key ID and Secret Access Key.
After you enable Sippy, requests for objects that are not yet in R2 are served from your source bucket and copied to R2. Subsequent requests for those objects are served from R2.
For setup instructions and credential requirements, refer to the Sippy documentation.
The agents, @cloudflare/ai-chat, @cloudflare/codemode, and @cloudflare/think packages now support AI SDK v6 and v7. Existing applications can remain on v6 when updating these packages. Applications can also adopt v7 without changing the Cloudflare Agents APIs they use.
The supported peer ranges are ai@^6 || ^7 and @ai-sdk/react@^3 || ^4. Use matching major versions: pair AI SDK v6 with @ai-sdk/react v3, or pair AI SDK v7 with @ai-sdk/react v4.
To install the latest packages with AI SDK v7:
npm i agents@latest @cloudflare/ai-chat@latest @cloudflare/codemode@latest @cloudflare/think@latest ai@^7 @ai-sdk/react@^4
bun add agents@latest @cloudflare/ai-chat@latest @cloudflare/codemode@latest @cloudflare/think@latest ai@^7 @ai-sdk/react@^4
Think normalizes streaming, tool completion events, and telemetry across both AI SDK versions. Existing v6 applications do not need to migrate these integrations before updating Think.
This release reduces repeated MCP schema conversion and adds an opt-out for Think's automatic MCP tool exposure. It also lets non-AI-SDK hosts invoke the durable Code Mode runtime directly.
Control direct MCP tool exposure in Think
Agents SDK MCP clients now reuse converted input and output schemas while a live connection keeps the same tool catalog. This avoids converting every MCP JSON Schema to Zod again for each model turn.
@cloudflare/think also adds includeMcpTools. Set it to false when you expose MCP tools through Code Mode or another mechanism outside Think's automatic tool set:
import { Think } from "@cloudflare/think";export class MyAgent extends Think { includeMcpTools = false; waitForMcpConnections = true;}
import { Think } from "@cloudflare/think";export class MyAgent extends Think<Env> { includeMcpTools = false; waitForMcpConnections = true;}
This setting skips Think's automatic getAITools() call. MCP registration, restoration, discovery, raw catalog access, direct calls, and Code Mode connectors continue to work.
@cloudflare/codemode@latest adds execute(), search(), and describe() to the durable runtime handle. MCP servers and other hosts can now execute code and discover connector methods without adapting the runtime to an AI SDK tool.
Search and describe results include requiresApproval: true for protected connector methods. Resolve a paused execution with the existing approve() and reject() methods.
This hotfix resolves a regression that caused a large increase in DNS-over-TCP queries to fallback and internal DNS servers. The client now sends fallback DNS queries over UDP first, falling back to TCP only when a response is truncated, instead of querying both protocols in parallel.
This hotfix resolves a regression that caused a large increase in DNS-over-TCP queries to fallback and internal DNS servers. The client now sends fallback DNS queries over UDP first, falling back to TCP only when a response is truncated, instead of querying both protocols in parallel.
This hotfix resolves a regression that caused a large increase in DNS-over-TCP queries to fallback and internal DNS servers. The client now sends fallback DNS queries over UDP first, falling back to TCP only when a response is truncated, instead of querying both protocols in parallel.
Review the Permission Groups API documentation; the response schema differs from the legacy Roles response.
Highlights
Integrations migrating to the Permission Groups API must obtain Permission Group IDs from that API and use them in the Account Members API policies request shape. Integrations that persist legacy Role IDs will need to remap their assignments.
The legacy Role response includes a top-level description and a permissions object keyed by resource type with edit/read flags.
The PermissionGroup response replaces those with a meta object containing label and scopes. Individual permissions are not returned as part of the permission group.
The new API supports the API Token authorization scheme. The legacy Email + API Key authorization schema is provided for backwards compatibility.
Devin Outposts ↗ lets you run Devin agents on Cloudflare. Each Devin session runs in its own isolated sandbox backed by Cloudflare Containers, so agents can execute code and use development tooling in an isolated environment.
Use Devin Outposts when you want Devin sessions to run on Cloudflare managed infrastructure, with each session isolated from the others.
Cloudflare now takes the guesswork out of TLS 1.3 key agreement with your origins. Automatic key exchange predicts the preferred algorithm and sends its key share in the first ClientHello, helping avoid a HelloRetryRequest and one extra network round trip.
Automatic key exchange is on for all existing zones and on by default for new zones. When an origin supports both classical and post-quantum key agreements, Cloudflare prefers the post-quantum X25519MLKEM768 hybrid key agreement.
To change this behavior, go to SSL/TLS > Overview > Origin connection & post-quantum encryption. Turn off Automatic key exchange to stop automatic scans and preference updates. Turning it off does not change your compliance requirements.
Compliance requirements apply only to TLS 1.3 connections. The Post-quantum hybrid option requires hybrid post-quantum key agreements support on your origin server. The Federal Information Processing Standards (FIPS) option requires FIPS-compliant key agreements. Select both to require key agreements that satisfy both, or leave both unselected to allow all supported key agreements.
This release introduces new rules for vulnerabilities in Adobe ColdFusion, Next.js, WordPress alongside updates to existing rules thereby providing enhanced generic protections against Server-Side Request Forgery (SSRF), Local File Inclusion (LFI), and Cross-Site Scripting (XSS).
WAF and framework adapter mitigations for Next.js vulnerabilities
Multiple security vulnerabilities ↗ were disclosed and patched by the Next.js team through July 2026 security release. These include denial of service, middleware and proxy bypass, server-side request forgery, information disclosure, and cache poisoning across a range of severities.
Several of the disclosed vulnerabilities are not possible to block at WAF layer,we strongly recommend updating your application and its dependencies immediately. Patched versions are available through v16.2.11 (Active LTS) and v15.5.21 (Maintenance LTS) to address these issues.
Crafted requests targeting Next.js applications using App Router with at least one Server Action can lead to excessive CPU usage. The CPU usage blocks processing of further requests in the same process, leading to Denial of Service.
WAF rule Next.js - DoS - CVE-2026-64641 () has been deployed to provide coverage.
Next.js applications using App Router built with Turbopack and a single entry in config.i18n.locales are vulnerable to a middleware/proxy bypass. Accordingly, any authentication or security checks that a middleware/proxy may perform are bypassed.
This is a middleware bypass that unfortunately cannot be covered through Cloudflare WAF signature engine.
A rewrites() or redirects() rule that builds its external destination hostname from request-controlled input can be pointed at an arbitrary hostname, regardless of the rule's hostname suffix. For rewrites, this behavior enables Server-Side Request Forgery (SSRF); for redirects, Open Redirect can be achieved.
Existing SSRF rules provide adequate coverage for this vulnerability, no tailored WAF rule was developed.
When a Server Action forwards or redirects a request, an attacker can cause the server to send that outbound request to a malicious host (Server-Side Request Forgery). This requires the attacker’s request to control Host-associated headers.
WAF rule Next.js - SSRF - CVE-2026-64649 () has been deployed to provide coverage.
When self-hosting Next.js with the default image loader, the Image Optimization API can optimize remotely hosted images if configured (not enabled by default). If those images contain malicious content, the images can cause CPU exhaustion in the /_next/image endpoint.
Malicious request is unfortunately indistinguishable from a legitimate image optimization request, so no WAF rule has been created to address this vulnerability.
A crafted request can lead to memory consumption on Server Actions in the Edge runtime. Next.js applications which use App Router and have at least one Server Action are affected.
Unfortunately there is no one size fits all rule that can be deployed through WAF in lieu of custom bodySizeLimit configurations, so no WAF rule has been created to address this vulnerability.
In Next.js applications using App Router, Server Actions (use server) or use cache endpoint IDs can be globally disclosed. An attacker can use this for reconnaissance and as part of a broader attack chain.
WAF rule Next.js - Information Disclosure - CVE-2026-64643 () has been deployed to provide coverage.
A server-side fetch with a request body may return a cached response body from a different request to the same URL but different body. This only applies for fetch calls of the shape fetch(new Request(init), aDifferentInit)
This is an application logic bug that unfortunately cannot be covered through Cloudflare WAF signature engine.
A server-side fetch with a request body may return a cached response body from a different request to the same URL but different body. This only applies when receiving request bodies which contain invalid UTF-8 characters.
This is an application logic bug that unfortunately cannot be covered through Cloudflare WAF signature engine.
Key Findings
CVE-2026-48276: A path traversal vulnerability in Adobe ColdFusion file upload mechanisms allows unauthenticated attackers to write or upload files to arbitrary locations outside designated directories on the origin server.
CVE-2026-48282: A path traversal vulnerability in Adobe ColdFusion enables unauthenticated attackers to manipulate directory sequences and access restricted system files on the host filesystem.
CVE-2026-60137: An unauthenticated SQL injection vulnerability affecting WordPress. Threat actors exploit unsanitized input parameters to execute arbitrary SQL queries, leading to unauthorized database access, record manipulation, or data exfiltration.
CVE-2026-63030: A remote code execution vulnerability affecting WordPress core and plugin components. Remote, unauthenticated attackers can execute arbitrary system commands to gain unauthorized access or establish backdoors on host servers.