CVE-2023-37303

An issue was discovered in the CheckUser extension for MediaWiki through 1.39.3. In certain...

9.8 CriticalFix available

An issue was discovered in the CheckUser extension for MediaWiki through 1.39.3. In certain situations, an attempt to block a user fails after a temporary browser hang and a DBQueryDisconnectedError error message.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

0.95%Up 0.9 points since Jul 1, 2023

What each source reports

NVD Score used 9.8

Record: CVE-2023-37303
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-754
Updated: 2026-11-02

CVE List No score

Record: CVE-2023-37303
Weakness: CWE-754
Updated: 2026-11-02

EUVDEUVD-2023-41207 No score

Record: EUVD-2023-41207
Updated: 2026-11-03

GitHub AdvisoriesGHSA-frhg-fmpg-fqp2 9.8

An issue was discovered in the CheckUser extension for MediaWiki through 1.39.3. In certain...

Record: GHSA-frhg-fmpg-fqp2
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-754
Updated: 2026-11-02

OSVUBUNTU-CVE-2023-37303 9.8

Record: UBUNTU-CVE-2023-37303
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVBIT-mediawiki-2023-37303 No score

Record: BIT-mediawiki-2023-37303
Updated: 2026-11-02

OSV No score

Record: CVE-2023-37303
Updated: 2026-11-02

Affected products

mediawiki

Affected packages

Affected packages
Package	Affected	Fixed
`mediawiki` Bitnami	before 1.39.4	1.39.4
`mediawiki` Ubuntu:18.04:LTS	All versions, plus listed versions 1:1.27.3-11:1.27.4-11:1.27.4-21:1.27.4-3	None known
`mediawiki` Ubuntu:Pro:20.04:LTS	All versions, plus listed versions 1:1.31.2-1ubuntu11:1.31.5-11:1.31.5-1ubuntu11:1.31.5-21:1.31.5-3 Show 4 moreShow less 1:1.31.5-3ubuntu11:1.31.6-11:1.31.7-11:1.31.7-1ubuntu0.1~esm1	None known
`mediawiki` Ubuntu:Pro:22.04:LTS	All versions, plus listed versions 1:1.35.3-11:1.35.4-11:1.35.5-11:1.35.5-1ubuntu11:1.35.5-1ubuntu21:1.35.5-1ubuntu31:1.35.6-11:1.35.6-1ubuntu0.1~esm1	None known
`mediawiki` Ubuntu:Pro:24.04:LTS	All versions, plus listed versions 1:1.39.4-21:1.39.5-11:1.39.6-11:1.39.7-11:1.39.7-1ubuntu0.1~esm1	None known
`mediawiki` Ubuntu:25.10	All versions, plus listed versions 1:1.43.1+dfsg-11:1.43.1+dfsg-21:1.43.3+dfsg-1	None known
`mediawiki` Ubuntu:26.10	All versions, plus listed versions 1:1.43.8+dfsg-21:1.43.9+dfsg-11:1.43.9+dfsg-1ubuntu1	None known
`mediawiki` Ubuntu:26.04:LTS	All versions, plus listed versions 1:1.43.3+dfsg-11:1.43.5+dfsg-11:1.43.6+dfsg-21:1.43.8+dfsg-11:1.43.8+dfsg-2	None known

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-37303 is a critical vulnerability (CVSS 9.8) in Mediawiki, published June 30, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.95%, the 61st percentile. Fixed in mediawiki 1.39.4.