DOMPurify: FORBID_TAGS bypassed by function-based ADD_TAGS predicate (asymmetry with FORBID_ATTR fix)

{
  "id": "e7305661d5220115ada9618af2f25ff4de9ad21e9cb926413cf76bf7a3dfc9c6",
  "url": "https://osv.dev/vulnerability/CVE-2026-41240",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DOMPurify: FORBID_TAGS bypassed by function-based ADD_TAGS predicate (asymmetry with FORBID_ATTR fix)",
    "summary": "DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Versions prior to 3.4.0 have an inconsistency between FORBID_TAGS and FORBID_ATTR handling when function-based ADD_TAGS is used. Commit c361baa added an early exit for FORBID_ATTR at line 1214. The same fix was not applied to FORBID_TAGS. At line 1118-1123, when EXTRA_ELEMENT_HANDLING.tagCheck returns true, the short-circuit evaluation skips the FORBID_TAGS check entirely. This allows forbidden elements to survive sanitization with their attributes intact. Version 3.4.0 patches the issue.",
    "evidence": "osv:CVE-2026-41240",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-41240",
      "aliases": [
        "CVE-2026-41240",
        "GHSA-h7mw-gpvr-xq4m"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/cure53/dompurify",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "5b16e0b892e82b1779d62b9928b43c4c4ff290b9"
                },
                {
                  "fixed": "c361baa18dbdcb3344a41110f4c48ad85bf48f80"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:cure53:dompurify:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "3.4.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c361baa18dbdcb3344a41110f4c48ad85bf48f80"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "5b16e0b892e82b1779d62b9928b43c4c4ff290b9"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "3.4.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "3.2.3",
            "3.1.3",
            "3.0.4",
            "2.4.3",
            "2.4.2",
            "2.4.1",
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            "2.0.1",
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            "1.0.7",
            "1.0.6",
            "1.0.5",
            "1.0.4",
            "1.0.3",
            "1.0.2",
            "1.0.1",
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            "0.9.0",
            "0.8.9",
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            "0.8.1",
            "0.8.0",
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            "0.7.1",
            "0.7.0",
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            "0.6.2",
            "0.6.1",
            "0.6.0",
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            "0.4.3",
            "0.4.2",
            "0.4",
            "0.3",
            "v0.3",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-41240.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.270946718Z",
      "provider": "osv",
      "references": [
        "https://github.com/cure53/DOMPurify/releases/tag/3.4.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41240.json",
        "https://github.com/cure53/DOMPurify/security/advisories/GHSA-h7mw-gpvr-xq4m",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-41240",
        "https://github.com/cure53/DOMPurify/commit/c361baa18dbdcb3344a41110f4c48ad85bf48f80"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-183",
          "CWE-79"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41240.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-41240",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497044,
  "published_at": "2026-04-23T14:54:32.426+00:00"
}