What is CVE-2023-37300?

CVE-2023-37300 is a medium-severity vulnerability in MediaWiki, classified under Incorrect Authorization. CVSS score: 5.3/10. Published 2023-06-30.

How severe is CVE-2023-37300?

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

Auth bypass in MediaWiki

CVE-2023-37300

An issue was discovered in the CheckUserLog API in the CheckUser extension for MediaWiki through 1.39.3. There is incorrect access control for visibility of hidden users.

Vulnerability class: Broken Access Control

Published 2023-06-30 · 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: 0.007 (50.1th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

MediaWiki

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

phabricator.wikimedia.org/T330968 (Exploit, Patch, Vendor Advisory)
gerrit.wikimedia.org/r/q/I993fdcae1fedb7dd543b35a477026bc727615b0a (Vendor Advisory)

Frequently asked questions

What is CVE-2023-37300?: CVE-2023-37300 is a medium-severity vulnerability in MediaWiki, classified under Incorrect Authorization. CVSS score: 5.3/10. Published 2023-06-30.
How severe is CVE-2023-37300?: Medium severity. CVSS v3 base score is 5.3 out of 10.