CVE-2026-59868

Description

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 5.2.0, when merge keys are enabled, js-yaml can spend quadratic CPU time parsing a document whose size grows only linearly when a chain of mappings uses merge keys where each mapping merges the previous one. This issue is fixed in version 5.2.0.

CVSS Metrics

• v3.1•MEDIUM•Score: 5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Techniques & Countermeasures

• CWE-407•Inefficient Algorithmic Complexity

  An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

Affected Systems

• nodeca•js-yaml

  ≥ 5.0.0, < 5.2.0

• Npm•js-yaml

  ≥ 5.0.0, < 5.2.0

References (5)

• https://github.com/nodeca/js-yaml/security/advisories/GHSA-g796-fgmg-93mv
• https://github.com/nodeca/js-yaml/commit/3105455b81dee69e0fd36e09ac0b2ccfdb54adc1
• https://github.com/nodeca/js-yaml/releases/tag/5.2.0
• https://nvd.nist.gov/vuln/detail/CVE-2026-59868
• https://github.com/nodeca/js-yaml