justhtml before 1.12.0 Sanitizer Bypass via Markdown

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-8445",
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "dateUpdated": "2026-08-23T13:34:13.886Z",
    "dateReserved": "2026-05-12T20:21:38.368Z",
    "datePublished": "2026-08-23T13:34:13.886Z",
    "state": "PUBLISHED"
  },
  "containers": {
    "cna": {
      "providerMetadata": {
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck",
        "dateUpdated": "2026-08-23T13:34:13.886Z"
      },
      "datePublic": "2026-03-18T00:00:00.000Z",
      "title": "justhtml before 1.12.0 Sanitizer Bypass via Markdown",
      "descriptions": [
        {
          "lang": "en",
          "value": "justhtml versions <= 1.11.0 (fixed in 1.12.0) do not sufficiently escape HTML-significant characters (angle brackets) in text nodes when converting a parsed document to Markdown via to_markdown(). While a small set of Markdown metacharacters are escaped, characters such as < and > are preserved, so untrusted input that is safe in to_html() — including entity-decoded text (e.g. &lt;script&gt;) or text from RCDATA/RAWTEXT-parsed elements like <title>, <textarea>, <noscript>, and <plaintext> — can be emitted as raw HTML in the Markdown output, enabling a sanitizer bypass and potential cross-site scripting when that output is rendered."
        }
      ],
      "affected": [
        {
          "vendor": "EmilStenstrom",
          "product": "justhtml",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "0",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "1.12.0"
            },
            {
              "version": "1.12.0",
              "status": "unaffected",
              "versionType": "semver"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')",
              "cweId": "CWE-79",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-3rcm-vjrc-p45j",
          "name": "GitHub Security Advisory (GHSA-3rcm-vjrc-p45j)",
          "tags": [
            "vendor-advisory"
          ]
        },
        {
          "url": "https://www.vulncheck.com/advisories/justhtml-before-sanitizer-bypass-via-markdown",
          "name": "VulnCheck Advisory: justhtml before 1.12.0 Sanitizer Bypass via Markdown",
          "tags": [
            "third-party-advisory"
          ]
        }
      ],
      "metrics": [
        {
          "format": "CVSS"
        },
        {
          "format": "CVSS",
          "cvssV3_1": {
            "version": "3.1",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "attackVector": "NETWORK",
            "attackComplexity": "LOW",
            "privilegesRequired": "NONE",
            "userInteraction": "NONE",
            "scope": "UNCHANGED",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "availabilityImpact": "HIGH",
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL"
          }
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "kejcao",
          "type": "reporter"
        }
      ]
    }
  }
}