{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "3.3.0"
              }
            ],
            "source": [
              "CPE_RANGE",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "15c3b79325125272263d7d42492ec8f757447191"
            },
            {
              "fixed": "a3cb6e5655308797e8be021d6c7b5bab13cbace2"
            },
            {
              "fixed": "067f90861088a496942f5eb43236135352b85d39"
            }
          ],
          "repo": "https://github.com/lepture/mistune",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-g97x-gvcm-x72h"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-79"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59926.json"
  },
  "details": "Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonition() in src/mistune/directives/admonition.py concatenates the Admonition directive :class: option into the HTML class attribute without escaping, allowing attribute injection and cross-site scripting even when HTMLRenderer escape mode is enabled. This issue is fixed in version 3.2.1.",
  "id": "CVE-2026-59926",
  "modified": "2026-08-07T11:31:06.813892617Z",
  "published": "2026-07-08T16:16:15.681Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/lepture/mistune/releases/tag/v3.2.1"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59926.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59926"
    },
    {
      "type": "FIX",
      "url": "https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Mistune: XSS via unescaped class option in Admonition directive"
}