{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.14.0"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "27f56428852decc3ca08b437f1cc9e0555384496"
            }
          ],
          "repo": "https://github.com/emilstenstrom/justhtml",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-r758-8hxw-4845"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-79"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5751.json"
  },
  "details": "justhtml versions 1.13.0 and earlier contain a parser-differential / mutation cross-site scripting (mXSS) vulnerability when using a custom SanitizationPolicy that preserves foreign namespaces (e.g., drop_foreign_namespaces=False with allowlisted SVG/MathML elements or raw-text containers such as \u003cstyle\u003e). Specially crafted input can sanitize into markup that appears safe but becomes unsafe when re-parsed by a browser or another HTML parser, allowing markup injection. The default safe configuration (sanitize=True) is not affected. Fixed in 1.14.0.",
  "id": "CVE-2026-5751",
  "modified": "2026-08-28T11:31:01.176990271Z",
  "published": "2026-08-23T13:34:10.547Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5751.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-r758-8hxw-4845"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-5751"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/justhtml-before-mutation-xss-via-custom-sanitization-policies"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "justhtml before 1.14.0 Mutation XSS via custom sanitization policies"
}