{"id":"CVE-2021-31553","aliases":["BIT-mediawiki-2021-31553","EUVD-2021-18450","GHSA-6475-q4qm-387r"],"status":"published","title":"An issue was discovered in the CheckUser extension for MediaWiki through 1.35.2. MediaWiki...","description":"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.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-12","score":0.01736,"percentile":0.78,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-428"],"published":"2021-04-22T02:29:31Z","modified":"2026-10-24T10:30:46Z","fixes":[{"ecosystem":"Bitnami","package":"mediawiki","fixed_in":["1.35.3"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Bitnami","package":"mediawiki","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.35.3"}]}]}],"products":[{"vendor":"mediawiki","product":"mediawiki"}],"references":[{"url":"https://phabricator.wikimedia.org/T275669","tags":["x_refsource_MISC","x_transferred","Third Party Advisory","web","advisory"]},{"url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667023","tags":["x_refsource_MISC","x_transferred","Issue Tracking","Third Party Advisory","web","report"]},{"url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667024","tags":["x_refsource_MISC","x_transferred","Issue Tracking","Third Party Advisory","web","report"]},{"url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667025","tags":["x_refsource_MISC","x_transferred","Issue Tracking","Third Party Advisory","web","report"]},{"url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667027","tags":["x_refsource_MISC","x_transferred","Issue Tracking","Third Party Advisory","web","report"]},{"url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666963","tags":["x_refsource_MISC","x_transferred","Issue Tracking","Third Party Advisory","web","report"]},{"url":"https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666964","tags":["x_refsource_MISC","x_transferred","Issue Tracking","Third Party Advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-31553","tags":["web"]},{"url":"https://github.com/advisories/GHSA-6475-q4qm-387r"}],"sources":{"cve":[{"id":"CVE-2021-31553","description":"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.","status":"published","published":"2021-04-22T02:29:31Z","modified":"2024-08-03T23:03:33.43Z","updated_at":"2026-11-02T14:33:05.331617Z"}],"euvd":[{"id":"EUVD-2021-18450","description":"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.","status":"published","published":"2021-04-22T02:29:31Z","modified":"2024-08-03T23:03:33Z","updated_at":"2026-11-03T03:24:38.977347Z"}],"ghsa":[{"id":"GHSA-6475-q4qm-387r","title":"An issue was discovered in the CheckUser extension for MediaWiki through 1.35.2. MediaWiki...","description":"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.","status":"published","published":"2022-05-24T17:48:08Z","modified":"2023-01-29T05:06:26Z","cwes":["CWE-428"],"updated_at":"2026-11-02T14:46:01.439998Z"}],"nvd":[{"id":"CVE-2021-31553","description":"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.","status":"published","published":"2021-04-22T03:15:08.197Z","modified":"2026-06-17T03:51:59.787Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"primary"},{"version":"2.0","score":6.4,"vector":"AV:N/AC:L/Au:N/C:N/I:P/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-428"],"updated_at":"2026-11-02T14:06:52.03307Z"}],"osv":[{"id":"CVE-2021-31553","description":"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.","status":"published","published":"2021-04-22T03:15:08.197Z","modified":"2026-10-24T10:30:46.754676232Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"updated_at":"2026-11-02T15:44:19.483607Z"},{"id":"BIT-mediawiki-2021-31553","description":"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.","status":"published","published":"2024-03-06T11:12:00.492Z","modified":"2025-04-03T14:40:37.652Z","updated_at":"2026-11-02T15:28:33.072289Z"}]}}