7.5

CVE-2026-34090: mediawiki checkuser

CVSS: 7.5v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-34090DEBIAN-CVE-2026-34090
Published 11-05-2026Last modified 11-05-2026
Open JSON

Vulnerability summary

CVE-2026-34090 is a high (CVSS 7.5) vulnerability in mediawiki checkuser. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 31% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
0.38%
0%100%
Low · +0.10 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 11-05-2026
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability information updated.

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 metrics

5 scores · 3 sources · 2 versions

EPSS trend

Probability

0.38%

Chance of exploitation in the next 30 days

Percentile

31%

Versus all other CVEs

30-day change

+0.10 pp

From 0.28% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.38%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Debian1 product
  • mediawikiAll versions (No fix recorded)
Mediawiki1 product
Ubuntu1 product
  • mediawikiAll versions (No fix recorded)
Wikimedia foundation1 product

4 vendors · 4 products

References

6 links