CVE-2026-53550

Summary

js-yaml is a JavaScript YAML parser and dumper. Prior to 4.2.0 and 3.15.0, a crafted YAML document can trigger algorithmic CPU exhaustion in js-yaml merge-key processing (<<) by repeating the same alias many times in a merge sequence. This causes quadratic parse-time behavior relative to input size and can block a Node.js worker/event loop for seconds with a relatively small payload (tens of KB), resulting in denial of service. The issue is in merge handling inside lib/loader.js. This vulnerability is fixed in 4.2.0 and 3.15.0.

Affected Software

VendorProductVersion RangeStatus
nodecajs-yaml>= 4.0.0, < 4.2.0affected
nodecajs-yaml< 3.15.0affected

Weaknesses

  • CWE-407: CWE-407: Inefficient Algorithmic Complexity

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

References