CVE-2026-59869 nodeca CVE debrief

Who should care

Users of js-yaml versions 3.0.0 to 3.14.0 and 4.0.0 to 4.2.0 should update to versions 3.15.0 or 4.3.0 to mitigate this vulnerability. Affected operators, platforms, and security teams should review their deployments and assess potential impact. Vulnerability management and security teams should prioritize this vulnerability due to its high CVSS score and potential for denial of service attacks.

Technical summary

js-yaml is vulnerable to a quadratic CPU time parsing issue when a chain of mappings uses merge keys where each mapping merges the previous one. This issue affects versions 3.0.0 to 3.14.0 and 4.0.0 to 4.2.0. The vulnerability is fixed in versions 3.15.0 and 4.3.0. Users of affected versions should update to mitigate this vulnerability. The vulnerability has a high CVSS score of 7.5, indicating a high severity.

Defensive priority

High priority due to high CVSS score of 7.5 and potential for denial of service attacks.

Recommended defensive actions

• Update js-yaml to version 3.15.0 or 4.3.0
• Review and update affected systems and applications
• Monitor for potential denial of service attacks
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide limited information about the vulnerability. Further analysis and testing may be necessary to fully understand the impact of this vulnerability. The vulnerability affects js-yaml versions 3.0.0 to 3.14.0 and 4.0.0 to 4.2.0. Users should verify their deployments and review official advisories for affected scope and severity. Defenders should check for potential denial of service attacks and monitor system logs.

Official resources