CVE-2021-31552

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-04-22 · updated 2026-06-17
Weakness: CWE-863

Description

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

Wikimedia Foundation MediaWiki: through 1.35.2

References

https://gerrit.wikimedia.org/r/q/I8bae477ad7e4d0190335363ac2decf28e4313da1
https://phabricator.wikimedia.org/T152394
https://gerrit.wikimedia.org/r/q/I8bae477ad7e4d0190335363ac2decf28e4313da1
https://phabricator.wikimedia.org/T152394

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