Cloudflare uses various cookies to maximize network resources, manage traffic, and protect our customers’ sites from malicious traffic.
Understanding the Cloudflare Cookies
__cflb cookie for Cloudflare Load Balancer session affinity
When enabling session affinity with Cloudflare Load Balancer, Cloudflare sets a
__cflb cookie with a unique value on the first response to the requesting client. Cloudflare routes future requests to the same origin, optimizing network resource usage. In the event of a failover, Cloudflare sets a new
__cflb cookie to direct future requests to the failover pool.
__cflb cookie allows Cloudflare to return an end user to the same customer origin for a specific period of time configured by the customer. This allows the end user to have a seamless experience (for example, this cookie is used for keeping an end user’s items in a shopping cart while they continue to navigate around the website). This cookie is a session cookie that lasts from several seconds up to 24 hours.
__cf_bm cookie for Cloudflare bot products
Cloudflare’s bot products identify and mitigate automated traffic to protect your site from bad bots. Cloudflare places the
__cf_bm cookie on end-user devices that access customer sites protected by Bot Management or Bot Fight Mode. The
__cf_bm cookie is necessary for these bot solutions to function properly.
This cookie expires after 30 minutes of continuous inactivity by the end user. The cookie contains information related to the calculation of Cloudflare’s proprietary bot score and, when Anomaly Detection is enabled on Bot Management, a session identifier. The information in the cookie (other than time-related information) is encrypted and can only be decrypted by Cloudflare.
__cf_bm cookie is generated for each site that an end user visits, as Cloudflare does not track users from site to site or from session to session. The
__cf_bm cookie is generated independently by Cloudflare, and does not correspond to any user ID or other identifiers in a customer’s web application.
cf_ob_info and cf_use_ob cookie for Cloudflare Always Online
cf_ob_info cookie provides information on:
- The HTTP Status Code returned by the origin web server
- The Ray ID of the original failed request
- The data center serving the traffic
cf_use_ob cookie informs Cloudflare to fetch the requested resource from the Always Online cache on the designated port. Applicable values are: 0, 80, and 443. The
cf_use_ob cookies are persistent cookies that expire after 30 seconds.
__cfwaitingroom for Cloudflare Waiting Room
Cloudflare’s Waiting Room product enables a waiting room for a particular host and path combination within a zone. Visitors are put in the waiting room and provided an estimate of when they will be allowed to access the application, if not immediately available.
__cfwaitingroom cookie is only used to track visitors that access a waiting room enabled host and path combination for a zone. Visitors using a browser that does not accept cookies cannot visit the host and path combination while the waiting room is active. For more details, refer to Waiting Room cookies.
__cfruid to support Cloudflare Rate Limiting (previous version)
__cfruid cookie is strictly necessary to support Cloudflare Rate Limiting products. As part of our Rate Limiting solution, this cookie is required to manage incoming traffic and to have better visibility on the origin of a particular request.
_cfuvid for Rate Limiting Rules
The Rate Limiting Rules product uses a number of techniques for applying rate limits to traffic where multiple unique visitors share the same IP address, such as traffic from behind a NAT. These techniques can be enabled by using the
cf.unique_visitor_id field in the rate limiting configuration.
_cfuvid cookie is only set when a site uses this option in a Rate Limiting Rule, and is only used to allow the Cloudflare WAF to distinguish individual users who share the same IP address. Visitors who do not provide the cookie are likely to be grouped together and may not be able to access the site if there are many other visitors from the same IP address.
Additional cookies used by the Challenge Platform
The table below shows additional cookies used by the Challenge Platform.
|Cookie Name (XXX represents dynamic part)||Description|
|Clearance Cookie stores the proof of challenge passed. It is used to no longer issue a challenge if present. It is required to reach an origin server.|
|This cookie is used to check whether the Cloudflare Edge server supports cookies. It can be deleted if seen.|
|These cookies are for internal use which allows Cloudflare to identify production issues on clients.|