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    CVE-2026-86435

    commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessive memory and CPU to exhaust server resources.

    Published:Sep 7, 2026
    Last Modified:Sep 9, 2026
    EPS:Sep 7, 2026
    EPSS Score:0.00279
    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-2026-86434 (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-2026-86430 (CVSS 8.7) — league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code bloc…
    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-2026-86435 — Thephpleague (High 8.7) | CVE-DB