SB2026070344 - Multiple vulnerabilities in js-yaml (npm)

Description

This security bulletin contains information about 2 vulnerabilities.

1) Inefficient Algorithmic Complexity (CVE-ID: CVE-2026-53550)

CWE-ID: CWE-407 - Inefficient Algorithmic Complexity

CVSSv4: 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/E:U/U:Green

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to algorithmic complexity in merge-key processing in lib/loader.js when parsing crafted YAML documents with repeated aliases in a merge sequence. A remote attacker can submit a specially crafted YAML document to cause a denial of service.

The issue causes quadratic parse-time behavior relative to input size and can block a Node.js worker or event loop for seconds with a relatively small payload.

2) Resource exhaustion (CVE-ID: N/A)

CWE-ID: CWE-400 - Resource exhaustion

CVSSv4: 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/E:U/U:Green

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to uncontrolled resource consumption in the js-yaml parser when parsing YAML documents containing chained merge keys. A remote attacker can send a specially crafted YAML document to cause a denial of service.

The issue results in quadratic CPU consumption for input whose size grows only linearly.

Remediation

Install update from vendor's website.

References

• https://github.com/nodeca/js-yaml/security/advisories/GHSA-h67p-54hq-rp68
• https://github.com/nodeca/js-yaml/security/advisories/GHSA-52cp-r559-cp3m