What is CVE-2021-44856?

CVE-2021-44856 is a medium-severity vulnerability in MediaWiki, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 5.3/10. Published 2022-12-26.

How severe is CVE-2021-44856?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in MediaWiki

CVE-2021-44856

An issue was discovered in MediaWiki before 1.35.5, 1.36.x before 1.36.3, and 1.37.x before 1.37.1. A title blocked by AbuseFilter can be created via Special:ChangeContentModel due to the mishandling of the EditFilterMergedContent hook return value.

Published 2022-12-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.005 (40.0th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 40.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

MediaWiki — versions 1.37.0

Weakness classification (CWE)

CWE-754 — Improper Check for Unusual or Exceptional Conditions

References

phabricator.wikimedia.org/T271037 (Patch, Issue Tracking, Vendor Advisory)
security.gentoo.org/glsa/202305-24

Frequently asked questions

What is CVE-2021-44856?: CVE-2021-44856 is a medium-severity vulnerability in MediaWiki, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 5.3/10. Published 2022-12-26.
How severe is CVE-2021-44856?: Medium severity. CVSS v3 base score is 5.3 out of 10.