CVE-2026-34090: medium-severity vulnerability in Wikimedia Foundation CheckUser
Suggested investigations: Handle suppressed usernames
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 4.8epss 0.3%
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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/R:U
Affected products
Wikimedia Foundation · CheckUserRelated CVEs — Wikimedia Foundation CheckUser
In the same product, most dangerous first.
CVE-2025-61649LOWUserInfoCard: Check that performing user has permission to view log entries for number of past blocksEPSS 0.4%CVE-2025-67478NONEWrong E-Mail address composition for usernames with a comma and Umlauts in it like "Döe, Jähn"EPSS 0.3%CVE-2025-61647LOWUserInfoCard: Don't allow access to information about users who are suppressed if you don't have suppressor rightsEPSS 0.3%CVE-2025-61650LOWUserInfoCard is vulnerable to message key stored XSSEPSS 0.3%CVE-2026-58034NONEStored XSS through a system message when blocking a temporary account that's related to other temporary accountsEPSS 0.3%CVE-2025-61658LOWSpecial:GlobalContributions shows edits on wikis the viewer doesn't have access toEPSS 0.3%