CVE-2026-59868 Details
Description
js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 5.2.0, when merge keys are enabled, 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 version 5.2.0.
A performance vulnerability has been identified in js-yaml, a JavaScript YAML parser and dumper, specifically in versions 5.0.0 prior to 5.2.0. When merge keys are enabled, js-yaml can experience quadratic CPU time consumption while parsing certain documents. This issue arises from a chain of mappings that use merge keys, where each mapping merges the previous one, leading to excessive processing time. The vulnerability is present in documents that, despite growing only linearly in size, create a parsing workload that increases quadratically due to the way merge keys are handled.
Users can update to js-yaml version 5.2.0 or later, where this vulnerability has been fixed. The default merge key limit in the updated version is set to 10,000, which should be sufficient for most use cases.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 9, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/nodeca/js-yaml/security/advisories/GHSA-g796-fgmg-93mv | CISA-ADP | ExploitVendor Advisory |
| https://github.com/nodeca/js-yaml/commit/3105455b81dee69e0fd36e09ac0b2ccfdb54adc1 | [email protected] | Patch |
| https://github.com/nodeca/js-yaml/releases/tag/5.2.0 | [email protected] | Release Notes |
| https://github.com/nodeca/js-yaml/security/advisories/GHSA-g796-fgmg-93mv | [email protected] | ExploitVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-770 | Allocation of Resources Without Limits or Throttling | [email protected] |
| CWE-407 | Inefficient Algorithmic Complexity | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| nodeca js-yaml | >= 5.0.0, < 5.2.0 |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 13, 2026 | Initial Analysis | [email protected] |
| Jul 9, 2026 | CVE Modified | CISA-ADP |
| Jul 8, 2026 | New CVE Received | [email protected] |