CVE-2021-30159

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-04-09 · updated 2026-06-17

Description

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. Users can bypass intended restrictions on deleting pages in certain "fast double move" situations. MovePage::isValidMoveTarget() uses FOR UPDATE, but it's only called if Title::getArticleID() returns non-zero with no special flags. Next, MovePage::moveToInternal() will delete the page if getArticleID(READ_LATEST) is non-zero. Therefore, if the page is missing in the replica DB, isValidMove() will return true, and then moveToInternal() will unconditionally delete the page if it can be found in the master.

Affected products

Debian Linux: 9.0, 10.0
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

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