CVE-2026-59870 nodeca CVE debrief

Who should care

Developers and administrators using js-yaml in their applications should be aware of this vulnerability and take steps to mitigate it. This includes updating js-yaml to version 5.2.1 or later, reviewing and validating input YAML data, and monitoring CPU consumption and performance of applications using js-yaml.

Technical summary

The vulnerability is caused by the use of omapTag.addItem() to perform a linear duplicate-key scan on every insertion in the !!omap tag in src/tag/sequence/omap.ts. This results in O(n^2) CPU consumption when yaml.load() parses a crafted ordered-map document. The vulnerability has been fixed in version 5.2.1. Affected products using js-yaml versions 5.0.0 to 5.2.0 should be updated to version 5.2.1 or later to mitigate this vulnerability. Developers and administrators should review and validate input YAML data to prevent crafted ordered-map documents and monitor CPU consumption and performance of applications using js-yaml.

Defensive priority

Medium

Recommended defensive actions

• Update js-yaml to version 5.2.1 or later
• Review and validate input YAML data to prevent crafted ordered-map documents
• Monitor CPU consumption and performance of applications using js-yaml
• 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 was published on 2026-07-08T16:16:33.580Z and last modified on 2026-07-10T18:01:31.563Z. The NVD entry is currently Awaiting Analysis. This information is based on the provided source corpus. Further verification is recommended to confirm affected scope and severity.

Official resources