CVE-2025-30157

Envoy's ext_proc HTTP filter is at risk of crashing if a local reply is sent to the external server due to the filter's life time issue. A known situation is the fail of a websocket handshake will trigger a local reply leading to the crash of Envoy.

PoC

If both websocket and ext_proc are enabled, a failed handshake will trigger a local reply, thus ext_proc will crash.

Mitigation

1. Disable websocket traffic
2. Change the websocket response from backend to always return 101 Switch protocol based on RFC.
3. Apply the patch and the ext_proc filter will not send the local reply that is generated by Envoy to the ext_proc server for processing.
4. Apply the patch that the router will cancel the upstream requests when sending a local reply.

Reporter

Vasilios Syrakis
Fernando Cainelli

Denial of service

CVE-2025-30157 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.30.10, 1.31.6, 1.32.4, 1.33.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-30157? CVE-2025-30157 is a medium-severity security vulnerability in github.com/envoyproxy/envoy (go), affecting versions < 1.30.10. It is fixed in 1.30.10, 1.31.6, 1.32.4, 1.33.1.
2. How severe is CVE-2025-30157? CVE-2025-30157 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/envoyproxy/envoy are affected by CVE-2025-30157? github.com/envoyproxy/envoy (go) versions < 1.30.10 is affected.
4. Is there a fix for CVE-2025-30157? Yes. CVE-2025-30157 is fixed in 1.30.10, 1.31.6, 1.32.4, 1.33.1. Upgrade to this version or later.
5. Is CVE-2025-30157 exploitable, and should I be worried? Whether CVE-2025-30157 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-30157 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-30157?
   • Upgrade github.com/envoyproxy/envoy to 1.30.10 or later
   • Upgrade github.com/envoyproxy/envoy to 1.31.6 or later
   • Upgrade github.com/envoyproxy/envoy to 1.32.4 or later
   • Upgrade github.com/envoyproxy/envoy to 1.33.1 or later