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    CVE-2026-71478

    league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.

    Published:Aug 6, 2026
    Last Modified:Aug 7, 2026
    EPS:Aug 6, 2026
    EPSS Score:0.00201
    CVSS Score:6.1

    Affected Products

    Vendor
    Thephpleague
    Product
    Commonmark

    Exploits

    No exploit reference

    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-2026-86430 (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…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
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    High
    User Interaction
    None
    Required
    Scope
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    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High