CVE-2026-59869CWE-407

js-yaml: YAML merge-key chains can force quadratic CPU consumption

High · published July 8, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
47.3
In the wild
Unconfirmed
What it is

js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 before 3.15.0 and from 4.0.0 before 4.3.0, js-yaml can spend quadratic CPU time parsing a document whose size grows only linearly when a chain of mappings uses merge keys where each mapping merges the previous one. This issue is fixed in versions 3.15.0 and 4.3.0.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00585 · 47.3th percentile
Weakness
CWE-407 · Inefficient Algorithmic Complexity
Published
2026-07-08T15:15Z
EPSS history
Timeline
  • 08 JUL 15:15Z
    js-yaml: YAML merge-key chains can force quadratic CPU consumption
    cvelistv5