A cache poisoning vulnerability has been found in the Pingora HTTP proxy framework’s default cache key construction. The issue occurs because the default HTTP cache key implementation generates cache keys using only the URI path, excluding critical factors such as the host header (authority). Operators relying on the default are vulnerable to cache poisoning, and cross-origin responses may be improperly served to users.


Impact

This vulnerability affects users of Pingora's alpha proxy caching feature who relied on the default CacheKey implementation. An attacker could exploit this for:

* Cross-tenant data leakage: In multi-tenant deployments, poison the cache so that users from one tenant receive cached responses from another tenant


* Cache poisoning attacks: Serve malicious content to legitimate users by poisoning shared cache entries




Cloudflare's CDN infrastructure was not affected by this vulnerability, as Cloudflare's default cache key implementation uses multiple factors to prevent cache key poisoning and never made use of the previously provided default.


Mitigation:

We strongly recommend Pingora users to upgrade to Pingora v0.8.0 or higher, which removes the insecure default cache key implementation. Users must now explicitly implement their own callback that includes appropriate factors such as Host header, origin server HTTP scheme, and other attributes their cache should vary on.


Pingora users on previous versions may also remove any of their default CacheKey usage and implement their own that should at minimum include the host header / authority and upstream peer’s HTTP scheme.

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Fixes

Solution

We strongly recommend Pingora users to upgrade to Pingora v0.8.0 or higher


Workaround

Pingora users on previous versions may also remove any of their default CacheKey usage and implement their own that should at minimum include the host header / authority and upstream peer’s HTTP scheme.

References
History

Thu, 05 Mar 2026 09:15:00 +0000

Type Values Removed Values Added
First Time appeared Cloudflare
Cloudflare pingora
Vendors & Products Cloudflare
Cloudflare pingora

Thu, 05 Mar 2026 00:00:00 +0000

Type Values Removed Values Added
Description A cache poisoning vulnerability has been found in the Pingora HTTP proxy framework’s default cache key construction. The issue occurs because the default HTTP cache key implementation generates cache keys using only the URI path, excluding critical factors such as the host header (authority). Operators relying on the default are vulnerable to cache poisoning, and cross-origin responses may be improperly served to users. Impact This vulnerability affects users of Pingora's alpha proxy caching feature who relied on the default CacheKey implementation. An attacker could exploit this for: * Cross-tenant data leakage: In multi-tenant deployments, poison the cache so that users from one tenant receive cached responses from another tenant * Cache poisoning attacks: Serve malicious content to legitimate users by poisoning shared cache entries Cloudflare's CDN infrastructure was not affected by this vulnerability, as Cloudflare's default cache key implementation uses multiple factors to prevent cache key poisoning and never made use of the previously provided default. Mitigation: We strongly recommend Pingora users to upgrade to Pingora v0.8.0 or higher, which removes the insecure default cache key implementation. Users must now explicitly implement their own callback that includes appropriate factors such as Host header, origin server HTTP scheme, and other attributes their cache should vary on. Pingora users on previous versions may also remove any of their default CacheKey usage and implement their own that should at minimum include the host header / authority and upstream peer’s HTTP scheme.
Title Cache poisoning via insecure-by-default cache key
References
Metrics cvssV4_0

{'score': 8.4, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: cloudflare

Published:

Updated: 2026-03-04T23:44:56.472Z

Reserved: 2026-02-19T21:33:42.425Z

Link: CVE-2026-2836

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-05T00:15:58.053

Modified: 2026-03-05T00:15:58.053

Link: CVE-2026-2836

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-03-05T09:05:30Z

Weaknesses

No weakness.