CVE-2021-30157

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-04-06 · updated 2026-06-17
Weakness: CWE-79

Description

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. On ChangesList special pages such as Special:RecentChanges and Special:Watchlist, some of the rcfilters-filter-* label messages are output in HTML unescaped, leading to XSS.

Affected products

Debian Linux: 10.0
Fedoraproject Fedora: 33, 34
Wikimedia Foundation MediaWiki: before 1.31.12; from 1.32.0 before 1.35.2 — fixed in 1.31.12, 1.35.2

How to fix

Upgrade to a fixed version: Wikimedia Foundation MediaWiki 1.31.12, 1.35.2. Check the vendor advisory for mitigations.

References

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/26UJGHF7LJDOCQN6A3Z4PM7PYRKENJHE/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2OMSV7B2TCFBOCICN3B4SMQP5HVRJQIT/
https://phabricator.wikimedia.org/T278058
https://security.gentoo.org/glsa/202107-40
https://www.debian.org/security/2021/dsa-4889
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/26UJGHF7LJDOCQN6A3Z4PM7PYRKENJHE/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2OMSV7B2TCFBOCICN3B4SMQP5HVRJQIT/
https://phabricator.wikimedia.org/T278058
https://security.gentoo.org/glsa/202107-40
https://www.debian.org/security/2021/dsa-4889

Get alerted when CVE-2021-30157 or the next vulnerability affects your stack