What’s Vulnerable › Vulnerabilities

CVE-2021-30156

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-04-09 · updated 2026-06-17
• Weakness: CWE-200

Description

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. Special:Contributions can leak that a "hidden" user exists.

Affected products

• Fedoraproject Fedora: 33, 34
• Wikimedia Foundation MediaWiki: before 1.31.12; from 1.32.0 before 1.35.2 — fixed in 1.31.12, 1.35.2

How to fix

Upgrade to a fixed version: Wikimedia Foundation MediaWiki 1.31.12, 1.35.2. Check the vendor advisory for mitigations.

References

• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/26UJGHF7LJDOCQN6A3Z4PM7PYRKENJHE/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2OMSV7B2TCFBOCICN3B4SMQP5HVRJQIT/
• https://phabricator.wikimedia.org/T276306
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/26UJGHF7LJDOCQN6A3Z4PM7PYRKENJHE/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2OMSV7B2TCFBOCICN3B4SMQP5HVRJQIT/
• https://phabricator.wikimedia.org/T276306

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