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Advisory severityHigh7.5Red Hat Linux

High [CVE-2026-59870] Denial of Service via crafted YAML ordered-map document

This high-severity Red Hat Linux advisory covers CVE-2026-59870 affecting Red Hat Hardened Images, Red Hat Discovery 2.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-59870 Source published Source updated

VulniPulse record published Record updated

CVE-2026-59870
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

Summary

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 5.2.1, YAML11_SCHEMA support for the!!omap tag in src/tag/sequence/omap.ts uses omapTag.addItem() to perform a linear duplicate-key scan on every insertion, causing O(n^2) CPU consumption when yaml.load() parses a crafted ordered-map document.

This issue is fixed in version 5.2.1. An attacker could exploit this by providing a specially crafted YAML ordered-map document.

This could lead to excessive CPU consumption, resulting in a denial of service (DoS) for applications processing the malicious YAML input. This affects yaml.load() calls using that schema.

Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-770.

Affected Red Hat products: Red Hat Hardened Images; Red Hat Discovery 2.

Is CVE-2026-59870 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-59870 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-59870?

Upgrade to a fixed release named by Red Hat:

  • 5.2.1
  • dotnet8-0-main-8.0.128-1.hum1
  • nodejs26-main-11.17.0-1.26.4.0.1.3.hum1
  • nodejs26-main-26.4.0-1.3.hum1
  • nodejs24-main-11.16.0-1.24.18.0.0.2.hum1
  • nodejs24-main-24.18.0-0.2.hum1
  • rust-main-1.96.1-1.hum1
  • nodejs22-main-10.9.8-1.22.23.1.2.hum1
  • nodejs22-main-22.23.1-2.hum1
  • nodejs25-main-11.12.1-1.25.9.0.1.1.hum1
  • nodejs25-main-25.9.0-1.1.hum1
  • yarnpkg-main-1.22.22-18.1.hum1

10 more fixed releases are listed below.

Confirm against the vendor advisory before you patch.

Affected versions
  • < 5.0.0
  • < 5.2.1

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

Fixed versions
  • 5.2.1
  • dotnet8-0-main-8.0.128-1.hum1
  • nodejs26-main-11.17.0-1.26.4.0.1.3.hum1
  • nodejs26-main-26.4.0-1.3.hum1
  • nodejs24-main-11.16.0-1.24.18.0.0.2.hum1
  • nodejs24-main-24.18.0-0.2.hum1
  • rust-main-1.96.1-1.hum1
  • nodejs22-main-10.9.8-1.22.23.1.2.hum1
  • nodejs22-main-22.23.1-2.hum1
  • nodejs25-main-11.12.1-1.25.9.0.1.1.hum1
  • nodejs25-main-25.9.0-1.1.hum1
  • yarnpkg-main-1.22.22-18.1.hum1
  • nodejs20-main-10.8.2-1.20.20.2.1.hum1
  • nodejs20-main-20.20.2-1.hum1
  • RHSA-2026:26994
  • RHSA-2026:33866
  • RHSA-2026:34478
  • RHSA-2026:34975
  • RHSA-2026:35272
  • RHSA-2026:7378
  • RHSA-2026:7655
  • RHSA-2026:9455

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Avoid using the YAML11_SCHEMA when parsing untrusted YAML input, or upgrade to js-yaml 5.2.1 or later. Applications using the default schema (CORE_SCHEMA) are not affected.

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

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