CVE record
CVE-2026-59869
js-yaml: YAML merge-key chains can force quadratic CPU consumption
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.
CVE evidence
Known exploitation
Not listed in fetched KEV catalog
Absence from the fetched catalog does not establish that exploitation has not occurred.
Severity
high
CVSS 7.5 · CVSS_V3
Affected packages
1
Supported package records returned by OSV. Vendor and product names are not used to infer matches.
OSV package mapping
Affected open-source packages
| Package | Ecosystem | Fixed versions |
|---|---|---|
| js-yaml | npm | 3.15.0, 4.3.0 |