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GHSA-8436-99hf-9mmv

undici vulnerable to caching and replay of unsafe HTTP method responses

Source: GitHub Advisory Database (reviewed) Low CVE-2026-85008

Packages

EcosystemPackageAffectedFixed in
npm undici >= 7.0.0, < 7.29.1 7.29.1
npm undici >= 8.0.0, < 8.10.2 8.10.2

Details

As written in the advisory (Markdown source, shown as plain text).

### Impact undici's `interceptors.cache()` documents that it caches only safe HTTP methods. However, its internal skip-list is built by subtracting the configured methods from the safe-methods set, so an unsafe method (`POST`, `PUT`, `PATCH`, `DELETE`) never lands in the skip-list and is looked up against the cache store. Combined with the storage gate (`canCacheResponse`) having no method check, a heuristically-cacheable response (for example a `404`) with an explicit `Cache-Control: max-age=...` to an unsafe method is stored and replayed on a subsequent identical request. The application's state-changing request never reaches the origin, and undici serves a fabricated response from the cache instead. This occurs with the default configuration (`methods: ['GET']`), which the public API does not allow widening to unsafe methods, so no application misuse is required; an untrusted origin can trigger it purely through its own response headers. ### Patches Upgrade to `7.29.1` or `8.10.2`. The cache interceptor no longer reads from or writes to the cache for unsafe HTTP methods, while still invalidating existing cache entries on successful unsafe requests. ### Workarounds None.

References

External links from the advisory. They lead to third-party sites.