🛡️ CVE-2021-31618 — apache

🟠 CVSS 8.0 — High ✅ No Known Exploit OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

NULL pointer dereference on specially crafted HTTP/2 request

Apache HTTP Server protocol handler for the HTTP/2 protocol checks received request headers against the size limitations as configured for the server and used for the HTTP/1 protocol as well. On violation of these restrictions and HTTP response is sent to the client with a status code indicating why the request was rejected. This rejection response was not fully initialised in the HTTP/2 protocol handler if the offending header was the very first one received or appeared in a a footer. This led to a NULL pointer dereference on initialised memory, crashing reliably the child process. Since such a triggering HTTP/2 request is easy to craft and submit, this can be exploited to DoS the server. This issue affected mod_http2 1.15.17 and Apache HTTP Server version 2.4.47 only. Apache HTTP Server 2.4.47 was never released.

Affected software

CVE-2021-31618 is recorded against 1 package.

  • apache

Timeline and source

Published on 6 March 2024 and last revised on 20 May 2025. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

httpd.apache.org (Web)
www.openwall.com (Web)
lists.apache.org (Web)
lists.apache.org (Web)
lists.debian.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
seclists.org (Web)
security.gentoo.org (Web)
security.netapp.com (Web)
www.debian.org (Web)
www.oracle.com (Web)
www.openwall.com (Web)
nvd.nist.gov (Web)

CVE-2021-31618 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector N/A
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2024-03-06
Updated 2026-08-12
Modified 2025-05-20
Fix URL N/A

Affected Packages

Software From version Fixed in
apache — —

References

Similar Threats

Site Security Check

Is apache part of your stack?

CVE-2021-31618 is rated CVSS 8.0 High. BotEraser scans your installation against known CVE records and tells you whether this vulnerability applies to the versions you actually run.

Scan My Site Free →

No credit card required  ·  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.