Description
In MediaWiki before 1.34.1, users can add various Cascading Style Sheets (CSS) classes (which can affect what content is shown or hidden in the user interface) to arbitrary DOM nodes via HTML content within a MediaWiki page. This occurs because jquery.makeCollapsible allows applying an event handler to any Cascading Style Sheets (CSS) selector. There is no known way to exploit this for cross-site scripting (XSS).
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | mediawiki | 1:1.31.7-1 | — |
| Debian 13 | mediawiki | 1:1.31.7-1 | — |
| Debian 12 | mediawiki | 1:1.31.7-1 | — |
| Debian 10 | mediawiki | 1:1.31.7-1~deb10u1 | DSA-4651-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | mediawiki | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Packagist | mediawiki/core | >= 1.31.0, < 1.31.7 | 1.31.7 | GHSA-pfm2-mqwj-ggm5 |
| Packagist | mediawiki/core | >= 1.33.0, < 1.33.3 | 1.33.3 | GHSA-pfm2-mqwj-ggm5 |
| Packagist | mediawiki/core | >= 1.34.0, < 1.34.1 | 1.34.1 | GHSA-pfm2-mqwj-ggm5 |
Advisories 1
- DSA-4651-1 mediawiki - security update Debian Security (DSA / DLA) · Mar 9, 2026