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GHSA-g2gp-3wwq-f4ph

GHSA-g2gp-3wwq-f4ph · league/commonmark: Denial of service via adjacent inline attribute blocks

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### Impact With the Attributes extension enabled, `AttributesListener::findTargetAndDirection()` resolves each attribute node's target by walking outward through its siblings. For a run of N adjacent inline attribute blocks placed at the start of a block (with nothing to their left), each node scans the **entire** sibling list to the far-right end before giving up and falling back to the parent. Each resolution is therefore Θ(N) and the whole run is **Θ(N²)**. Reaching the path requires `AttributesExtension` (opt-in, but first-party: `League\CommonMark\Extension\Attributes\AttributesExtension`). No other configuration matters — the quadratic walk runs unconditionally during parsing and is **not** gated by the `attributes/allow` allow-list, the `on*` hardening added in 2.7.0, or `allow_unsafe_links`. An unauthenticated attacker can submit a **~32 KB** input (`{#a}` repeated 8,000 times) that takes **over 5 seconds** to convert, with time growing quadratically in input length — a cheap denial of service. Availability impact only. **The Attributes extension was introduced in 1.5.0 (May 2020) with this outward-walk resolver present from the first commit, so all releases from 1.5.0 onward (including every 2.x) are affected.** ### Workarounds There is no library-level configuration that gates the quadratic walk. Integrators who cannot upgrade can only reduce exposure indirectly: - **Disable the Attributes extension** for untrusted input, or - **Impose a strict maximum input length before conversion** — noting that because the cost is quadratic, even a modest cap must be small to meaningfully bound worst-case CPU. Upgrading to a release containing the fix is recommended.

CVSS 7.5 · Высокий · Есть исправление

Опубликовано
Обновлено

Стек: php

Затронутые продукты и версии

  • league/commonmark Packagist

    Версии
    • 1.5.0
    • 1.5.1
    • 1.5.2
    • 1.5.3
    • 1.5.4
    • 1.5.5
    • 1.5.6
    • 1.5.7
    • 1.5.8
    • 1.6.0
    • 1.6.1
    • 1.6.2
    • 1.6.3
    • 1.6.4
    • 1.6.5
    • 1.6.6
    • 1.6.7
    • 2.0.0
    • 2.0.0-beta1
    • 2.0.0-beta2
    • 2.0.0-beta3
    • 2.0.0-rc1
    • 2.0.0-rc2
    • 2.0.1
    • 2.0.2
    • 2.0.3
    • 2.0.4
    • 2.1.0
    • 2.1.1
    • 2.1.2
    • 2.1.3
    • 2.2.0
    • 2.2.1
    • 2.2.2
    • 2.2.3
    • 2.2.4
    • 2.2.5
    • 2.3.0
    • 2.3.1
    • 2.3.2
    • 2.3.3
    • 2.3.4
    • 2.3.5
    • 2.3.6
    • 2.3.7
    • 2.3.8
    • 2.3.9
    • 2.4.0
    • 2.4.1
    • 2.4.2
    • 2.4.3
    • 2.4.4
    • 2.5.0
    • 2.5.1
    • 2.5.2
    • 2.5.3
    • 2.6.0
    • 2.6.1
    • 2.6.2
    • 2.7.0
    • 2.7.1
    • 2.8.0
    • 2.8.1
    • 2.8.2
    • 2.8.3
    Затронутые диапазоны версий
    • ECOSYSTEM: ≥ 1.5.0, < 2.9.0

    Обновитесь до 2.9.0

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