Envoy Proxy NULL Pointer Dereference Vulnerability - CVE-2025-64527

Envoy is a high-performance edge/middle/service proxy. In 1.33.12 1.34.10 1.35.6 1.36.2 and earlier Envoy crashes when JWT authentication is configured with the remote JWKS fetching allow_missing_or_failed is enabled multiple JWT tokens are present in the request headers and the JWKS fetch fails. This is caused by a re-entry bug in the JwksFetcherImpl. When the first token39s JWKS fetch fails onJwksError() callback triggers processing of the second token which calls fetch() again on the same fetcher object. The original callback39s reset() then clears the second fetch39s state (receiver_ and request_) which causes a crash when the async HTTP response arrives.