{"id":"CVE-2021-31553","details":"An issue was discovered in the CheckUser extension for MediaWiki through 1.35.2. MediaWiki usernames with trailing whitespace could be stored in the cu_log database table such that denial of service occurred for certain CheckUser extension pages and functionality. For example, the attacker could turn off Special:CheckUserLog and thus interfere with usage tracking.","aliases":["BIT-mediawiki-2021-31553"],"modified":"2026-07-09T00:14:10.570908Z","published":"2021-04-22T03:15:08.197Z","references":[{"type":"ADVISORY","url":"https://phabricator.wikimedia.org/T275669"},{"type":"REPORT","url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666963"},{"type":"REPORT","url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666964"},{"type":"REPORT","url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667023"},{"type":"REPORT","url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667024"},{"type":"REPORT","url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667025"},{"type":"REPORT","url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667027"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/wikimedia/mediawiki","events":[{"introduced":"0"},{"last_affected":"e5823c068a2e0d8af72538fe5cd152ddb43c58e9"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"last_affected":"1.35.2"}],"source":"CPE_RANGE","cpe":"cpe:2.3:a:mediawiki:mediawiki:*:*:*:*:*:*:*:*"}}],"versions":["1.35.2","1.35.1","1.35.0","1.35.0-rc.3","1.35.0-rc.2","1.35.0-rc.1","1.35.0-rc.0","test-hashar-for-ci","1.6.0","1.5.0beta4","1.5.0beta3","1.5.0beta2","1.5.0beta1","1.5.0alpha2","1.5.0alpha1","1.3.0beta1","1.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-31553.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L"}]}