What’s Vulnerable › Vulnerabilities

CVE-2021-44857

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-12-17 · updated 2026-06-17
• Weakness: CWE-862

Description

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. It is possible to use action=mcrundo followed by action=mcrrestore to replace the content of any arbitrary page (that the user doesn't have edit rights for). This applies to any public wiki, or a private wiki that has at least one page set in $wgWhitelistRead.

Affected products

• Wikimedia Foundation MediaWiki: before 1.35.5; from 1.36.0 before 1.36.3; from 1.37.0 before 1.37.1 — fixed in 1.35.5, 1.36.3, 1.37.1

How to fix

Upgrade to a fixed version: Wikimedia Foundation MediaWiki 1.35.5, 1.36.3, 1.37.1. Check the vendor advisory for mitigations.

References

• https://phabricator.wikimedia.org/T297322
• https://security.gentoo.org/glsa/202305-24
• https://www.mediawiki.org/wiki/2021-12_security_release/FAQ
• https://phabricator.wikimedia.org/T297322
• https://security.gentoo.org/glsa/202305-24
• https://www.mediawiki.org/wiki/2021-12_security_release/FAQ

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