CVE-2026-59869
js-yaml: YAML merge-key chains can force quadratic CPU consumption
CVSS Score
7.5
EPSS Score
0.4%
EPSS Percentile
27th
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.
| CWE | CWE-407 |
| Vendor | nodeca |
| Product | js-yaml |
| Published | Jul 8, 2026 |
| Last Updated | Jul 9, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
nodeca / js-yaml
>= 3.0.0, < 3.15.0 >= 4.0.0, < 4.3.0
References
github.com: https://github.com/nodeca/js-yaml/security/advisories/GHSA-52cp-r559-cp3m github.com: https://github.com/nodeca/js-yaml/commit/24f13e79ee1343a7e30bd6f6c9d9cdbf0ac9b2b7 github.com: https://github.com/nodeca/js-yaml/commit/59423c6f8cdc78742ac00e25a4dd39ef16b702e4 github.com: https://github.com/nodeca/js-yaml/releases/tag/3.15.0 github.com: https://github.com/nodeca/js-yaml/releases/tag/4.3.0