# CVE-2025-64527: ecs-service-connect-agent: Envoy is a high-performance edge/middle/service proxy

CVE-2025-64527 is fixed in ecs-service-connect-agent on 1 platform by ALAS2023-2025-1357 (version v1.34.4.2-1.amzn2023), released January 7, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2025-64527
- Priority: High
- CVSS: n/a (important)
- EPSS: 0.0056
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jan 7, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | ecs-service-connect-agent amzn 2023 | v1.34.4.2-1.amzn2023 | [ALAS2023-2025-1357](https://patchblox.com/security/data/fix/linux/alas2023-2025-1357.md) | Jan 7, 2026 |

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Data as of 2026-11-11T13:47:35Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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