CVE-2026-34090

HIGH

Suggested investigations: Handle suppressed usernames

Title source: cna

Description

Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Wikimedia Foundation CheckUser. This issue affects CheckUser: from 1.45.0 before 1.45.2.

References (1)

Core 1

Core References

https://phabricator.wikimedia.org/T411366

Scores

CVSS v3 7.5

EPSS 0.0003

EPSS Percentile 10.4%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-200

Status published

Products (2)

mediawiki/checkuser 1.45.0 - 1.45.2

Wikimedia Foundation/CheckUser 1.45.0 - 1.45.2

Published May 11, 2026

Tracked Since May 11, 2026