CVE-2021-31552

Name: CVE-2021-31552
Creator: NVD / NIST
Published: 2021-04-22T03:15:08.163+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 0.58%

Last modified Jun 17, 2026

CVE-2021-31552 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. 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. EPSS estimates a 0.58% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS Probability

0.58%

43.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-863

Affected Software

Vendor	Product	Versions
Mediawiki	Mediawiki	<= 1.35.2

References

https://gerrit.wikimedia.org/r/q/I8bae477ad7e4d0190335363ac2decf28e4313da1Issue Tracking, Vendor Advisory
https://phabricator.wikimedia.org/T152394Third Party Advisory
https://gerrit.wikimedia.org/r/q/I8bae477ad7e4d0190335363ac2decf28e4313da1Issue Tracking, Vendor Advisory
https://phabricator.wikimedia.org/T152394Third Party Advisory

Timeline

Published: Apr 22, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31552?

How severe is CVE-2021-31552?

CVE-2021-31552 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.58% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31552?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-31552?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST