Vulnerability · Published May 11, 2026 · Assigned by wikimedia-foundation
CVE-2026-34091User localization leaked by AbuseFilter + EventStream
Medium 5.5
In plain English
A medium-severity information exposure in MediaWiki from Wikimedia Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 4.0)5.5Medium
Exploit odds (30 days)0.3%top 78.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Wikimedia Foundation MediaWiki. This issue affects MediaWiki: from * before 1.43.7, 1.44.4, 1.45.2.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | mediawiki | 1:1.43.8+dfsg-1~deb13u1 | DEBIAN-CVE-2026-34091 |
| Debian:14 | mediawiki | 1:1.43.8+dfsg-1 | DEBIAN-CVE-2026-34091 |
| Ubuntu:25.10 | mediawiki | no fix listed | UBUNTU-CVE-2026-34091 |
| Ubuntu:26.04:LTS | mediawiki | 1:1.43.8+dfsg-2 | UBUNTU-CVE-2026-34091 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Wikimedia Foundation | MediaWiki | * – before 1.43.7, 1.44.4, 1.45.2 |
Weakness: CWE-200 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/R:U