Mistune: Potential DoS via quadratic-time parsing in parse_link_text_CVE-2026-49851

{
    "lastseen": "",
    "description": "Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Mistune is vulnerable to a CPU exhaustion DoS due to superlinear (approximately O(n\u00b2)) behavior in parse_link_text. When parsing Markdown containing many consecutive [ characters, parse_link_text repeatedly scans the input using a regex search inside a loop. Each iteration re-scans a large portion of the remaining string, resulting in quadratic-time behavior. An attacker-controlled Markdown input can therefore trigger excessive CPU usage with a very small payload. This vulnerability is fixed in 3.3.0.",
    "published": "2026-06-24T17:05:33.602Z",
    "modified": "2026-06-24T17:05:33.602Z",
    "type": "cve",
    "title": "Mistune: Potential DoS via quadratic-time parsing in parse_link_text",
    "source": "GitHub_M",
    "references": "https://github.com/lepture/mistune/security/advisories/GHSA-qcq2-496w-v96p",
    "id": "CVE-2026-49851",
    "bulletinFamily": "",
    "cwe": [
        "CWE-400",
        "CWE-770",
        "CWE-407"
    ],
    "cvelist": null,
    "sourceData": "lepture mistune < 3.3.0",
    "sourceHref": "",
    "cvss": {
        "score": 8.7,
        "severity": "HIGH",
        "vector": "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",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "mistune",
    "version": "< 3.3.0",
    "vendor": "lepture",
    "ai_description": "CPU exhaustion DoS via quadratic-time parsing in parse_link_text",
    "ai_severity": "High",
    "ai_vendor": "lepture",
    "ai_product": "Mistune",
    "ai_version": "< 3.3.0",
    "ai_score": 8.7
}