CVE-2021-41799

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-10-11 · updated 2026-06-17
Weakness: CWE-770

Description

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.

Affected products

Fedoraproject Fedora: 33, 34, 35
Wikimedia Foundation MediaWiki: before 1.36.2 — fixed in 1.36.2

How to fix

Upgrade to a fixed version: Wikimedia Foundation MediaWiki 1.36.2. Check the vendor advisory for mitigations.

References

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CJDYJQWT43GBD6GNQ4OW7JOZ6WQ6DZTN/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MDBPECBWN6LWNSWIQMVXK6PP4YFEUYHA/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QNEAI2T3Y65I55ZB6UE6RMC662RZTGRX/
https://lists.wikimedia.org/hyperkitty/list/wikitech-l%40lists.wikimedia.org/thread/2IFS5CM2YV4VMSODPX3J2LFHKSEWVFV5/
https://phabricator.wikimedia.org/T290394
https://security.gentoo.org/glsa/202305-24
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CJDYJQWT43GBD6GNQ4OW7JOZ6WQ6DZTN/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MDBPECBWN6LWNSWIQMVXK6PP4YFEUYHA/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QNEAI2T3Y65I55ZB6UE6RMC662RZTGRX/
https://lists.wikimedia.org/hyperkitty/list/wikitech-l%40lists.wikimedia.org/thread/2IFS5CM2YV4VMSODPX3J2LFHKSEWVFV5/
https://phabricator.wikimedia.org/T290394
https://security.gentoo.org/glsa/202305-24

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