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    CVE-2026-86433

    commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Attributes extension where AttributesListener::findTargetAndDirection() performs quadratic-time sibling list scanning. Unauthenticated attackers can submit approximately 32 KB of repeated attribute blocks to cause parsing to take over 5 seconds, exhausting server resources.

    Published:Sep 7, 2026
    Last Modified:Sep 8, 2026
    EPS:Sep 7, 2026
    EPSS Score:0.00291
    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

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    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