CVE-2026-34090
Suggested investigations: Handle suppressed usernames
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- Passive
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Suggested investigations: Handle suppressed usernames
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.
- Record
CVE-2026-34090- CVSS 4.0
- 4.8 Medium
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 - Weakness
- CWE-200
- Updated
- 2026-11-02
EUVDEUVD-2026-29062
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.
- Record
EUVD-2026-29062- CVSS 4.0
- 4.8 Medium
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-cg3w-6fh3-65mw
Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Wikimedia Foundation...
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.
- Record
GHSA-cg3w-6fh3-65mw- CVSS 4.0
- 4.8 Medium
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:U/V:X/RE:X/U:X - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-34090- CVSS 4.0
- 4.8 Medium
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:U/V:X/RE:X/U:X - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-34090
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.
- Record
UBUNTU-CVE-2026-34090- CVSS 4.0
- 4.8 Medium
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-34090 is a medium vulnerability (CVSS 4.8) in Mediawiki Checkuser, published April 3, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.28%, the 20th percentile. No source names a fixed version.
References
phabricator.wikimedia.org/T411366
nvd.nist.gov/vuln/detail/CVE-2026-34090
github.com/advisories/GHSA-cg3w-6fh3-65mw
security-tracker.debian.org/tracker/CVE-2026-34090
ubuntu.com/security/CVE-2026-34090
cve.org/CVERecord?id=CVE-2026-34090
gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/1240641
lists.wikimedia.org/hyperkitty/list/[email protected]/thread/DIBLSBHISKX6NFRUFNOGZRVW42E7R2QP