Cloudflare Pingora up to 0.8.x HTTP/2 Proxy req_header Host access control

Summaryinfo

A vulnerability marked as very critical has been reported in Cloudflare Pingora up to 0.8.x. Affected by this vulnerability is the function req_header of the component HTTP2 Proxy. This manipulation of the argument Host causes access control. This vulnerability is tracked as CVE-2026-105298. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as very critical was found in Cloudflare Pingora up to 0.8.x. Affected by this vulnerability is the function req_header of the component HTTP2 Proxy. The manipulation of the argument Host with an unknown input leads to a access control vulnerability. The CWE definition for the vulnerability is CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Summary Before version 0.9.0, Pingora accepted HTTP/2 requests whose Host header differed from the :authority pseudo-header. Request filters, cache keys, and logs that read the request URI (session.req_header().uri) saw the :authority value, but the upstream received the client-supplied Host value. Pingora also accepted :authority values containing userinfo (for example, [email protected]). This violates RFC 9113 Section 8.3.1, which requires an intermediary to use the :authority value for Host and replace any existing Host field. Root cause * HTTP/2 to HTTP/1.1: Host was generated from :authority only when the request had no Host header, so a conflicting client Host was forwarded unchanged. * HTTP/2 to HTTP/2: the client Host header was removed and used to overwrite the upstream :authority, after request filters had already run against the original :authority. * The HTTP/2 server did not compare Host with :authority and did not reject userinfo in the authority. Impact A remote, unauthenticated attacker can send a single HTTP/2 request that the application sees as one host and the upstream receives as another. Where request filters, access controls, or cache keys use the URI authority and the upstream routes by Host, this can lead to: * Cache poisoning: a response from another virtual host is stored under the victim host's cache key and served to other users (this also requires the upstream to serve different content per Host). * Host-based access control bypass: a request approved for one host is served by a different virtual host on the upstream. Deployments that do not accept HTTP/2 from clients, or that do not use the request authority for security or caching decisions, are not affected. Note that Cloudflare CDN customers were unaffected, as internal Pingora services at Cloudflare do not have HTTP/2 clients. Mitigation: * Upgrade to pingora 0.9.0 or later. Pingora now returns 400 Bad Request for HTTP/2 requests whose Host differs from :authority, that contain more than one Host, or whose authority contains userinfo, and keeps the upstream Host or :authority consistent with the request authority. Fix commits: https://github.com/cloudflare/pingora/commit/915590a91811877795531f6ba0927a3138b5cb4b , https://github.com/cloudflare/pingora/commit/ffab8302d08d4292d1924eb8fe84647fd5cb8e76 * If you cannot upgrade: in request_filter, reject HTTP/2 requests that carry a Host header different from the URI authority, or whose authority contains '@'.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-105298 since 10/05/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/20/2026). The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

Upgrading to version 0.9.0 eliminates this vulnerability. Applying the patch 915590a91811877795531f6ba0927a3138b5cb4b/ffab8302d08d4292d1924eb8fe84647fd5cb8e76 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Cloud Software

Vendor

• Cloudflare

Name

• Pingora

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8

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CPE 2.2info

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