Description
Mediawiki v1.40.0 does not validate namespaces used in XML files.
Therefore, if the instance administrator allows XML file uploads,
a remote attacker with a low-privileged user account can use this
exploit to become an administrator by sending a malicious link to
the instance administrator.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| MediaWiki | MediaWiki | 1.40.0 | — |
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 | 1:1.39.5-1 | — |
| Debian 13 | mediawiki | 1:1.39.5-1 | — |
| Debian 12 | mediawiki | 1:1.39.5-1~deb12u1 | DSA-5520-1 |
| Debian 11 | mediawiki | 1:1.35.13-1~deb11u1 | DSA-5520-1 |
| Debian 10 | mediawiki | 1:1.31.16-1+deb10u7 | DLA-3671-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | mediawiki | No fix yet | — |
| Ubuntu 26.04 LTS | mediawiki | No fix yet | — |
| Ubuntu 25.10 | mediawiki | No fix yet | — |
| Ubuntu 18.04 LTS | mediawiki | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | mediawiki | No fix yet | — |
| Ubuntu Pro 20.04 LTS | mediawiki | No fix yet | — |
Advisories 3
- DSA-5520-1 mediawiki - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-3671-1 mediawiki - security update Debian Security (DSA / DLA) · Mar 9, 2026
- WID-SEC-2023-2442 MediaWiki: Schwachstelle ermöglicht Erlangen von Administratorrechten BSI CERT-Bund (WID) · May 5, 2024
References
- https://fluidattacks.com/advisories/blondie/
- https://www.mediawiki.org/wiki/MediaWiki/
- https://www.debian.org/security/2023/dsa-5520
- https://lists.debian.org/debian-lts-announce/2023/11/msg00027.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FU2FGUXXK6TMV6R52VRECLC6XCSQQISY/