High severity · published May 11, 2026
CVE-2026-34090
Suggested investigations: Handle suppressed usernames
7.5
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 20% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CH
CheckUser · Wikimedia Foundation
1.45.0 before 1.45.2 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34090
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-34090
Issue Tracking
https://phabricator.wikimedia.org/T411366
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Special:GlobalContributions shows edits on wikis the viewer doesn't have access to