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CVE-2026-59870

CVE-2026-59870 · js-yaml quadratic-complexity denial of service via YAML11_SCHEMA !!omap parsing

This page contains facts from public vulnerability sources. Check the original advisory before updating.

js-yaml is a JavaScript YAML parser and dumper. Prior to 3.15.1, 4.3.1, and 5.2.1, YAML11_SCHEMA support for the !!omap tag in src/tag/sequence/omap.ts uses omapTag.addItem() to perform a linear duplicate-key scan on every insertion, causing O(n^2) CPU consumption when yaml.load() parses a crafted ordered-map document. In v3 and v4, !!omap is active and exploitable by default. v5 doesn't use !!omap by default, and the chances of activating it are very low.This issue is fixed in 3.15.1, 4.3.1, and 5.2.1.

CVSS 7.5 · High · EPSS 0.7% · Fix available

Published
Updated

Stack: system · node

Affected products and versions

  • js-yaml

    Versions
    • >= 5.0.0, < 5.2.1: Affected
    • >= 3.0.0, < 3.15.1: Affected
    • >= 4.0.0, < 4.3.1: Affected

    No fix published

  • js-yaml npm

    Affected ranges
    • SEMVER: ≥ 5.0.0, < 5.2.1

    Update to 5.2.1

  • node-js-yaml Ubuntu:18.04:LTS

    Versions
    • 3.9.1+dfsg-1
    • 3.10.0+dfsg-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-js-yaml Ubuntu:20.04:LTS

    Versions
    • 3.13.1+dfsg-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-js-yaml Ubuntu:22.04:LTS

    Versions
    • 3.14.1+dfsg+~3.12.6-2
    • 4.1.0+dfsg+~4.0.5-4ubuntu1
    • 4.1.0+dfsg+~4.0.5-5
    • 4.1.0+dfsg+~4.0.5-6
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-js-yaml Ubuntu:24.04:LTS

    Versions
    • 4.1.0+dfsg+~4.0.5-7
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-js-yaml Ubuntu:25.10

    Versions
    • 4.1.0+dfsg+~4.0.5-7
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-js-yaml Ubuntu:26.10

    Versions
    • 4.1.1+dfsg+~4.0.9-1
    • 4.2.0+~4.0.9-1
    • 4.2.0+~4.0.9-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-js-yaml Ubuntu:26.04:LTS

    Versions
    • 4.1.0+dfsg+~4.0.5-7
    • 4.1.1+dfsg+~4.0.9-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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