CVE-2026-23918

Published May 4, 2026

Last updated a month ago

CVSS high 8.8
Ubuntu
Server
Port (80)
Port (443)
HTTP

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-23918 is a double-free vulnerability found in Apache HTTP Server's `mod_http2` module, specifically within the HTTP/2 protocol handling. This flaw affects Apache HTTP Server version 2.4.66. The vulnerability is triggered when a client sends an HTTP/2 HEADERS frame immediately followed by an RST_STREAM frame with a non-zero error code on the same stream, before the stream has been fully registered by the multiplexer. This sequence causes the `h2_stream` pointer to be pushed onto a cleanup array twice, leading to a double-free when `c1_purge_streams` attempts to destroy the stream and its associated memory pool a second time. Exploitation of this vulnerability can lead to a denial-of-service condition, where the Apache worker crashes, dropping requests. Additionally, it can potentially enable remote code execution by manipulating the freed memory to place a fake `h2_stream` structure and execute arbitrary commands. The issue has been addressed in Apache HTTP Server version 2.4.67, and users of affected versions are recommended to upgrade.

Description
Double Free and possible RCE vulnerability in Apache HTTP Server with the HTTP/2 protocol. This issue affects Apache HTTP Server: 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.
Source
security@apache.org
NVD status
Modified
Products
http_server

Risk scores

CVSS 3.1

Type
Secondary
Base score
8.8
Impact score
5.9
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity
HIGH

Weaknesses

security@apache.org
CWE-415
0b0ca135-0b70-47e7-9f44-1890c2a1c46c
CWE-1341

Social media

Hype score
Not currently trending

  1. 🛡️ SUSE-SU-2026:2641-1: 10 CVEs corrigidas no Apache2, incluindo RCE via HTTP/2 (CVE-2026-23918) e estouro de heap no mod_proxy_ajp (CVE-2026-28780). Saiba mais: -> https://t.co/mG59ffwQJd #SUSE https://t.co/Wi9lcnOT2X

    @Cezar_H_Linux

    26 Jun 2026

    74 Impressions

    0 Retweets

    0 Likes

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    1 Reply

    0 Quotes

  2. 60% · CVE-2026-23918 · 2.4.67 → 2.4.17 Apache Software Foundation shipped Apache HTTP Server 2.4.67 on May 4, 2026 to address five security vulnerabilities.

    @lyrie_ai

    13 Jun 2026

    18 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    1 Reply

    0 Quotes

  3. CVE-2026-23918 · 2.4.66 → 2.4.67 The Scoreboard Trap: CVE-2026-23918 Apache HTTP/2 Double-Free Now Has a Working RCE PoC

    @lyrie_ai

    4 Jun 2026

    36 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    1 Reply

    0 Quotes

  4. Critical Apache HTTP/2 Flaw (CVE-2026-23918) Enables DoS and Potential RCE. https://t.co/TSJZOPPWHG

    @KlinkWow769

    17 May 2026

    34 Impressions

    0 Retweets

    1 Like

    0 Bookmarks

    1 Reply

    0 Quotes

  5. CVE-2026-34486: PoCs for Apache Tomcat Unauth RCE (CVE-2026-34486) and Apache httpd Pre-auth RCE (CVE-2026-23918) are now public on our Github. Tomcat exploit is fully reliable. httpd chain works in a controlled lab setup with a known info leak.

    @lyrie_ai

    12 May 2026

    62 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    1 Reply

    0 Quotes

  6. #exploit 1⃣ CVE-2026-31431: Code exec into containers sharing the same image layer https://t.co/1WHHD88uAH 2⃣ CVE-2025-68670: RCE in the xrdp server https://t.co/X8AYExy9VJ 3⃣ CVE-2026-23918: Apache mod_http2 vulnerability https://t.co/pBdyEHb0GL // Disclaimer

    @ksg93rd

    11 May 2026

    390 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  7. Apache HTTP Serverに遠隔コード実行の脆弱性。CVE-2026-23918はCVSSスコア8.8の二重解放。HTTP/2実装の"early stream reset"シーケンスにおけるもの。2025/12/10報告、12/11修正コミット、2026/5/4公式修正リリース。 https://t.co/wQGy0z5

    @__kokumoto

    6 May 2026

    1247 Impressions

    2 Retweets

    9 Likes

    3 Bookmarks

    0 Replies

    0 Quotes

Configurations

Related CVEs

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References

Sources include official advisories and independent security research.