Inefficient Algorithmic Complexity in js-yaml (npm) - #VU140666
Published: August 1, 2026
Vulnerability identifier: #VU140666
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-407
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 inefficient algorithmic complexity in readFlowCollection in parser.ts when parsing untrusted YAML flow collections via load() or loadAll(). A remote attacker can send a specially crafted small YAML document to cause a denial of service.
A single request can keep one CPU busy for minutes or longer and block the Node event loop, which can stall the whole process.
Affected software
js-yaml (npm)
Remediation
Install security update from vendor's website.
js-yaml (npm) - update to 5.2.2