CVE-2021-31552: Mediawiki

Medium severity, CVSS 5.4. EPSS: 0.6% chance of exploitation in the next 30 days.

An issue was discovered in the AbuseFilter extension for MediaWiki through 1.35.2. It incorrectly executed certain rules related to blocking accounts after account creation. Such rules would allow for user accounts to be created while blocking only the IP address used to create an account (and not the user account itself). Such rules could also be used by a nefarious, unprivileged user to catalog and enumerate any number of IP addresses related to these account creations.

Affected products

• Mediawiki Mediawiki: up to and including 1.35.2

Published 2021-04-22. Last modified 2026-06-17.