CVE-2026-50572: Envoy: ext_authz - RawHttpClientImpl onSuccess 0x0 segfault

Vulnerability summary

CVE-2026-50572 is a medium (CVSS 5.9) Use After Free vulnerability in envoyproxy envoy. EPSS estimates a 0.68% chance of exploitation in the next 30 days, higher than 51.8% of scored vulnerabilities.

Timeline

1. 21-09-2026
   PublishedVulnerability first disclosed.
2. 22-09-2026
   Last modifiedVulnerability information updated.

Description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's HTTP external-authorization client can retain a stale request callback after a request is rejected. When RawHttpClientImpl::onSuccess later processes the authorization response, it can invoke callbacks_ after the callback owner has been destroyed, causing a use-after-free and process crash under production traffic. The relevant scope boundary is that the vulnerable path uses the HTTP ext_authz client; the advisory does not establish the same trigger for unrelated filters. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

• CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.