CVE-2023-35945: Envoyproxy Envoy

High severity, CVSS 7.5. EPSS: 1.3% chance of exploitation in the next 30 days.

Envoy is a cloud-native high-performance edge/middle/service proxy. Envoy’s HTTP/2 codec may leak a header map and bookkeeping structures upon receiving `RST_STREAM` immediately followed by the `GOAWAY` frames from an upstream server. In nghttp2, cleanup of pending requests due to receipt of the `GOAWAY` frame skips de-allocation of the bookkeeping structure and pending compressed header. The error return [code path] is taken if connection is already marked for not sending more requests due to `GOAWAY` frame. The clean-up code is right after the return statement, causing memory leak. Denial of service through memory exhaustion. This vulnerability was patched in versions(s) 1.26.3, 1.25.8, 1.24.9, 1.23.11.

Affected products

• Envoyproxy Envoy: before 1.23.11 (fixed in 1.23.11); from 1.24.0, before 1.24.9 (fixed in 1.24.9); from 1.25.0, before 1.25.8 (fixed in 1.25.8); from 1.26.0, before 1.26.3 (fixed in 1.26.3)
• NGHTTP2 NGHTTP2: before 1.55.1 (fixed in 1.55.1)

Published 2023-07-13. Last modified 2026-06-17.