# CVE-2026-59869: js-yaml: YAML merge-key chains can force quadratic CPU consumption

> CVE-2026-59869: js-yaml: YAML merge-key chains can force quadratic CPU consumption. CVSS 7.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-59869
Last updated: 2026-10-25T20:10:00Z

- Published: 2026-07-08 15:15 UTC · Updated: 2026-10-25 20:10 UTC · Assigner: GitHub\_M
- CVSS: 7.5 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS: 0.58%, 48th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-407

## Description

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.

## Affected vendors and products

- nodeca: js-yaml

## Tracked companies

- [Bitbucket](https://rewindex.com/company/bitbucket.md)
- [Jira](https://rewindex.com/company/jira.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-59869)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-59869)
- [https://github.com/nodeca/js-yaml/commit/24f13e79ee1343a7e30bd6f6c9d9cdbf0ac9b2b7](https://github.com/nodeca/js-yaml/commit/24f13e79ee1343a7e30bd6f6c9d9cdbf0ac9b2b7)
- [https://github.com/nodeca/js-yaml/commit/59423c6f8cdc78742ac00e25a4dd39ef16b702e4](https://github.com/nodeca/js-yaml/commit/59423c6f8cdc78742ac00e25a4dd39ef16b702e4)
- [https://github.com/nodeca/js-yaml/releases/tag/3.15.0](https://github.com/nodeca/js-yaml/releases/tag/3.15.0)
- [https://github.com/nodeca/js-yaml/releases/tag/4.3.0](https://github.com/nodeca/js-yaml/releases/tag/4.3.0)
- [https://github.com/nodeca/js-yaml/security/advisories/GHSA-52cp-r559-cp3m](https://github.com/nodeca/js-yaml/security/advisories/GHSA-52cp-r559-cp3m)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-59869 · Markdown: https://rewindex.com/cve/CVE-2026-59869.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-59869 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:14:48.124Z