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    CVE-2026-86430

    league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. Attackers can submit specially crafted Markdown with long backtick runs, nested brackets, or delimiter sequences to consume disproportionate CPU time and prevent legitimate requests from completing.

    Published:Sep 7, 2026
    Last Modified:Sep 7, 2026
    EPS:Sep 7, 2026
    EPSS Score:
    CVSS Score:7.5

    Affected Products

    Vendor
    Thephpleague
    Product
    Commonmark

    Exploits

    No exploit reference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

    Related CVEs

    CVE-2024-58382 (CVSS 8.7) — league/commonmark versions before 2.6.0 contain polynomial time complexity vulnerabilities in Markdown parsing…
    CVE-2026-86435 (CVSS 8.7) — commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extensio…
    CVE-2026-86434 (CVSS 8.7) — league/commonmark versions >= 2.0.0 and < 2.8.4 (patched in 2.9.0) contain a denial of service vulnerability i…
    CVE-2026-86433 (CVSS 8.7) — commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Attributes extens…
    CVE-2026-86432 (CVSS 6.9) — commonmark versions from 2.0.0 before 2.8.4 contain a denial of service vulnerability in XmlRenderer that emit…
    CVE-2026-86431 (CVSS 6.9) — league/commonmark (thephpleague/commonmark) versions >= 2.7.0 and < 2.9.1 contain a cross-site scripting vulne…
    CVE-2026-86429 (CVSS 8.7) — The league/commonmark (thephpleague/commonmark) library in versions >= 1.5.0 and < 2.9.1 contains quadratic pa…
    CVE-2026-86428 (CVSS 8.7) — commonmark versions from 1.5.0 before 2.10.0 contain a denial of service vulnerability in the AttributesExtens…
    CVE-2026-71488 (CVSS 7.5) — league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 0.6.0 until 2.9.0, spec…
    CVE-2026-71478 (CVSS 6.1) — league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the …

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2026-86430 — Thephpleague (High 8.7) | CVE-DB