Security advisory

{
  "id": "2b209d7ed662f9715eac3a79cd7ff6fb67bf05d7dae8931ce7ab0cfb5675b7c1",
  "url": "https://osv.dev/vulnerability/CVE-2021-31553",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-31553",
    "summary": "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.",
    "evidence": "osv:CVE-2021-31553",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-31553",
      "aliases": [
        "BIT-mediawiki-2021-31553",
        "CVE-2021-31553"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/wikimedia/mediawiki",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "e5823c068a2e0d8af72538fe5cd152ddb43c58e9"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:mediawiki:mediawiki:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "1.35.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "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"
          }
        }
      ],
      "modified": "2026-10-24T10:30:46.754676232Z",
      "provider": "osv",
      "references": [
        "https://phabricator.wikimedia.org/T275669",
        "https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666963",
        "https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666964",
        "https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667023",
        "https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667024",
        "https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667025",
        "https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667027"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-31553",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 436399,
  "published_at": "2021-04-22T03:15:08.197+00:00"
}