CVE-2026-2836 is a low severity vulnerability with a CVSS score of 0.0. No known exploits currently, and patches are available.
Very low probability of exploitation
EPSS predicts the probability of exploitation in the next 30 days based on real-world threat data, complementing CVSS severity scores with actual risk assessment.
Pingora versions prior to 0.8.0 generated cache keys using only the URI path, excluding critical factors such as the host header. This allows an attacker to poison the cache and serve cross-origin responses to users.
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, or serve malicious content to legitimate users by poisoning shared cache entries.
Note: Cloudflare customers and Cloudflare's CDN infrastructure were 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.
We strongly suggest users should upgrade to Pingora v.0.8.0 or higher, which removes the default CacheKey implementation.
Do not rely on the provided CacheKey default, and at minimum use the host / :authority and the upstream peer TLS scheme as part of building the CacheKey, as well as other factors that may apply to the deployment e.g. HTTP method.
See CVE-2026-2836 and the Cloudflare blog post for more details.
Disclosed responsibly by Rajat Raghav (@xclow3n) through the Cloudflare Bug Bounty Program.
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