---
id: CVE-2023-35945
title: Envoy is a cloud-native high-performance edge/middle/service proxy
summary: >-
  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…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
  - CWE-459
vendor: envoyproxy
product: envoy
affected:
  - envoy < 1.23.11
  - 'envoy >= 1.24.0, < 1.24.9'
  - 'envoy >= 1.25.0, < 1.25.8'
  - 'envoy >= 1.26.0, < 1.26.3'
  - nghttp2 < 1.55.1
patched:
  - envoy 1.26.3
  - nghttp2 1.55.1
published: '2023-07-13'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T00:16:33.813'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2023-35945'
references:
  - url: >-
      https://github.com/envoyproxy/envoy/security/advisories/GHSA-jfxv-29pc-x22r
    label: security-advisories@github.com
  - url: >-
      https://github.com/nghttp2/nghttp2/blob/e7f59406556c80904b81b593d38508591bb7523a/lib/nghttp2_session.c#L3346
    label: security-advisories@github.com
  - url: >-
      https://github.com/envoyproxy/envoy/security/advisories/GHSA-jfxv-29pc-x22r
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://github.com/nghttp2/nghttp2/blob/e7f59406556c80904b81b593d38508591bb7523a/lib/nghttp2_session.c#L3346
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-943925.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.01652
epssPercentile: 0.76152
ingestedAt: '2026-10-15T01:08:04.203Z'
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2024-10-31T16:24:45.853511Z'
---

## Overview

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

- `envoy < 1.23.11`
- `envoy >= 1.24.0, < 1.24.9`
- `envoy >= 1.25.0, < 1.25.8`
- `envoy >= 1.26.0, < 1.26.3`
- `nghttp2 < 1.55.1`

## Remediation

Upgrade past the affected range:

- `envoy 1.26.3`
- `nghttp2 1.55.1`