Resource exhaustion in js-yaml (npm) - CVE-2026-59870
Published: July 3, 2026
Vulnerability identifier: #VU136865
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-59870
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in omapTag.addItem() in the !!omap tag handling for YAML11_SCHEMA when parsing crafted YAML input with yaml.load(). A remote attacker can send a specially crafted YAML document to cause a denial of service.
Only applications that parse untrusted YAML with { schema: yaml.YAML11_SCHEMA } are vulnerable.
Affected software
js-yaml (npm)
How to mitigate CVE-2026-59870
Install security update from vendor's website.
js-yaml (npm) - update to 5.2.1