What is CVE-2021-31545?

CVE-2021-31545 is a medium-severity vulnerability in MediaWiki, classified under Information Disclosure. CVSS score: 5.3/10. Published 2021-04-22.

How severe is CVE-2021-31545?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Information disclosure in MediaWiki

CVE-2021-31545

An issue was discovered in the AbuseFilter extension for MediaWiki through 1.35.2. The page_recent_contributors leaked the existence of certain deleted MediaWiki usernames, related to rev_deleted.

Vulnerability class: Information Disclosure

Published 2021-04-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.008 (55.9th percentile), scored 2026-10-07.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 55.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

MediaWiki

Weakness classification (CWE)

CWE-200 — Information Disclosure

References

phabricator.wikimedia.org/T71367 (Third Party Advisory)
gerrit.wikimedia.org/r/q/I8d5ed9ca84282ee50832035af86123633fc88293 (Issue Tracking, Vendor Advisory)

Frequently asked questions

What is CVE-2021-31545?: CVE-2021-31545 is a medium-severity vulnerability in MediaWiki, classified under Information Disclosure. CVSS score: 5.3/10. Published 2021-04-22.
How severe is CVE-2021-31545?: Medium severity. CVSS v3 base score is 5.3 out of 10.