CVE-2021-41799

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query...

7.5 HighFix available

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query processing time). ApiQueryBacklinks (action=query&list=backlinks) can cause a full table scan.

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: None
Integrity: None
Availability: High

Exploit likelihood

1.70%Up 0.9 points since Oct 11, 2021

What each source reports

NVD Score used 7.5

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query processing time). ApiQueryBacklinks (action=query&list=backlinks) can cause a full table scan.

Record: CVE-2021-41799
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness: CWE-770
Updated: 2026-11-02

CVE List No score

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query processing time). ApiQueryBacklinks (action=query&list=backlinks) can cause a full table scan.

Record: CVE-2021-41799
Updated: 2026-11-02

EUVDEUVD-2021-28807 No score

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query processing time). ApiQueryBacklinks (action=query&list=backlinks) can cause a full table scan.

Record: EUVD-2021-28807
Updated: 2026-11-03

GitHub AdvisoriesGHSA-h7pp-5ppj-95mv 7.5

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query...

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query processing time). ApiQueryBacklinks (action=query&list=backlinks) can cause a full table scan.

Record: GHSA-h7pp-5ppj-95mv
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-770
Updated: 2026-11-02

OSV 7.5

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query processing time). ApiQueryBacklinks (action=query&list=backlinks) can cause a full table scan.

Record: CVE-2021-41799
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2021-41799 7.5

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query processing time). ApiQueryBacklinks (action=query&list=backlinks) can cause a full table scan.

Record: DEBIAN-CVE-2021-41799
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2021-41799 7.5

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query processing time). ApiQueryBacklinks (action=query&list=backlinks) can cause a full table scan.

Record: UBUNTU-CVE-2021-41799
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVBIT-mediawiki-2021-41799 No score

MediaWiki before 1.36.2 allows a denial of service (resource consumption because of lengthy query processing time). ApiQueryBacklinks (action=query&list=backlinks) can cause a full table scan.

Record: BIT-mediawiki-2021-41799
Updated: 2026-11-02

OSVMGASA-2021-0477 No score

Updated mediawiki packages fix security vulnerability

XSS vulnerability in Special:Search. (CVE-2021-41798) ApiQueryBacklinks can cause a full table scan. (CVE-2021-41799) Fix PoolCounter protection of Special:Contributions. (CVE-2021-41800) ReplaceText continues performing actions if the user no longer has the correct permission (such as by being blocked). (CVE-2021-41801)

Record: MGASA-2021-0477
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`mediawiki` Bitnami	before 1.36.2	1.36.2
`mediawiki` Debian:12	before 1:1.35.4-1	1:1.35.4-1
`mediawiki` Debian:13	before 1:1.35.4-1	1:1.35.4-1
`mediawiki` Debian:14	before 1:1.35.4-1	1:1.35.4-1
`mediawiki` Debian:9 From an advisory covering 3 CVEs	before 1:1.27.7-1~deb9u10, plus listed versions 1:1.27.3-11:1.27.4-11:1.27.4-1~bpo8+11:1.27.4-1~deb9u11:1.27.4-2 Show 12 moreShow less 1:1.27.4-31:1.27.5-1~deb9u11:1.27.6-1~deb9u11:1.27.7-1~deb9u11:1.27.7-1~deb9u21:1.27.7-1~deb9u31:1.27.7-1~deb9u41:1.27.7-1~deb9u51:1.27.7-1~deb9u61:1.27.7-1~deb9u71:1.27.7-1~deb9u81:1.27.7-1~deb9u9	1:1.27.7-1~deb9u10
`mediawiki` Debian:10 From an advisory covering 5 CVEs	before 1:1.31.16-1~deb10u1, plus listed versions 1:1.31.10-1~deb10u11:1.31.12-1~deb10u11:1.31.14-1~deb10u11:1.31.2-11:1.31.4-1 Show 9 moreShow less 1:1.31.4-1~deb10u11:1.31.5-11:1.31.5-21:1.31.5-31:1.31.6-11:1.31.6-1~deb10u11:1.31.7-11:1.31.7-1~deb10u11:1.31.8-1	1:1.31.16-1~deb10u1
`mediawiki` Debian:11 From an advisory covering 5 CVEs	before 1:1.35.4-1~deb11u1, plus listed versions 1:1.35.2-11:1.35.3-1	1:1.35.4-1~deb11u1
`mediawiki` Mageia:8 From an advisory covering 4 CVEs	before 1.35.4-1.mga8	1.35.4-1.mga8
`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

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Affected packages
Package	Affected	Fixed
`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 6, 2026	affected, facts
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-2021-41799 is a high vulnerability (CVSS 7.5) in Mediawiki, published October 1, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.70%, the 77th percentile. Fixed in mediawiki 1.36.2.

References

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