CVE-2026-59870 | js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 b… | CVSS 5.3 MEDIUM

Description

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 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. This issue is fixed in version 5.2.1.

Metadata

CVE ID: CVE-2026-59870
State: PUBLISHED
Assigner: GitHub_M
Reserved: 2026-07-07 15:41 UTC
Published: 2026-07-08 15:13 UTC
Last updated: 2026-07-08 15:50 UTC
Primary CWE: CWE-407
CWE-407: Inefficient Algorithmic Complexity
Vendor / Product: nodeca / js-yaml
Sources: cve.org · NVD

Severity & Metrics

5.3 MEDIUM CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

SSVC — CISA Coordinator

Exploitation: PoC
Automatable: yes
Tech. Impact: partial

Affected products (1)

Vendor	Product	Platform	Versions
nodeca	js-yaml	—	>= 5.0.0, < 5.2.1

Weakness (CWE)

CWE	Source	Description
CWE-407	cna	CWE-407: Inefficient Algorithmic Complexity

CVSS scores (1)

Score	Severity	Version	Source	Vector
5.3	MEDIUM	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References (3)

https://github.com/nodeca/js-yaml/security/advisories/GHSA-724g-mxrg-4qvm https://github.com/nodeca/js-yaml/security/advisories/GHSA-724g-mxrg-4qvm
https://github.com/nodeca/js-yaml/commit/39f3211a2f01b3c6982710cf21434ab7060acefe https://github.com/nodeca/js-yaml/commit/39f3211a2f01b3c6982710cf21434ab7060acefe
https://github.com/nodeca/js-yaml/releases/tag/5.2.1 https://github.com/nodeca/js-yaml/releases/tag/5.2.1