What’s Vulnerable › Vulnerabilities

CVE-2021-36126

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-07-02 · updated 2026-06-17

Description

An issue was discovered in the AbuseFilter extension in MediaWiki through 1.36. If the MediaWiki:Abusefilter-blocker message is invalid within the content language, the filter user falls back to the English version, but that English version could also be invalid on a wiki. This would result in a fatal error, and potentially fail to block or restrict a potentially nefarious user.

Affected products

• Wikimedia Foundation MediaWiki: through 1.36

References

• https://gerrit.wikimedia.org/r/q/I9e9f44b7663e810de70fb9ac7f6760f83dd4895b
• https://phabricator.wikimedia.org/T284364
• https://gerrit.wikimedia.org/r/q/I9e9f44b7663e810de70fb9ac7f6760f83dd4895b
• https://phabricator.wikimedia.org/T284364

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