In short
- CVE-2025-64527 is a MEDIUM (CVSS 6.5) vulnerability affecting github.com/envoyproxy/envoy, envoy (envoyproxy).
- Chance of exploitation in the next 30 days (EPSS): 0.53%, higher than 44.9% of all vulnerabilities.
- Fix: update to 1.34.11, 1.35.7, 1.36.3, 1.33.13 or later.
| Package | Affected versions | Patched versions |
|---|
| github.com/envoyproxy/envoy Go | ≥ 1.34.0, < 1.34.11≥ 1.35.0, < 1.35.7≥ 1.36.0, < 1.36.3< 1.33.13
| 1.34.111.35.71.36.31.33.13
|
| envoy | ≥ 1.34.0, < 1.34.11≥ 1.35.0, < 1.35.7≥ 1.36.0, < 1.36.3< 1.33.13
| 1.34.111.35.71.36.31.33.13
|
Description
Summary
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.
Details
This is caused by a re-entry bug in the JwksFetcherImpl. When the first token's JWKS fetch fails, onJwksError() callback triggers processing of the second token, which calls fetch() again on the same fetcher object.
The original callback's reset() then clears the second fetch's state (receiver_ and request_) which causes a crash when the async HTTP response arrives.
PoC
allow_missing_or_failed or allow_missing is enabled- The client send 2 Authorization headers
- the remote JWKS fetching failed
- There will be crash
Impact
DoS and Crash
Mitigation
- Disable the
allow_missing_or_failed or allow_missing
NVD description
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 token's JWKS fetch fails, onJwksError() callback triggers processing of the second token, which calls fetch() again on the same fetcher object. The original callback's reset() then clears the second fetch's state (receiver_ and request_) which causes a crash when the async HTTP response arrives.
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