CVE-2026-34091: User localization leaked by AbuseFilter + EventStream

Published May 11, 2026
·
Updated

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 Software

4 affected components
Wikimedia Foundation MediaWiki<1.43.7, <1.44.4, <1.45.2
MediaWiki MediaWiki<1.43.7
MediaWiki MediaWiki>=1.44.0<1.44.4
MediaWiki MediaWiki>=1.45.0<1.45.2

Event History

May 11, 2026
CVE Published
via MITRE·02:55 PM
Data Sourced
via MITRE·02:55 PM
DescriptionWeakness
Data Sourced
via NVD·04:17 PM
DescriptionSeverityWeaknessAffected Software
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Frequently Asked Questions

1

What is the severity of CVE-2026-34091?

The severity of CVE-2026-34091 is considered to be high due to the exposure of sensitive user localization information.

2

How do I fix CVE-2026-34091?

To fix CVE-2026-34091, upgrade MediaWiki to version 1.43.7 or later, or to version 1.44.4 or later, or to version 1.45.2 or later.

3

What systems are affected by CVE-2026-34091?

CVE-2026-34091 affects MediaWiki versions prior to 1.43.7, 1.44.4, and 1.45.2.

4

What kind of information is leaked in CVE-2026-34091?

CVE-2026-34091 leaks user localization data, which can potentially expose sensitive information to unauthorized actors.

5

Who is responsible for fixing CVE-2026-34091 vulnerabilities?

It is the responsibility of the system administrators and users running affected versions of MediaWiki to apply the necessary updates to mitigate CVE-2026-34091.

Company

Resources

Contact

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CVE-2026-34091 - User localization leaked by AbuseFilter + EventStream - SecAlerts