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Fencer Intel
high 7.5

CVE-2026-59869 json

js-yaml: YAML merge-key chains can force quadratic CPU consumption

published 4mo ago modified 17d ago also EUVD-2026-42301 , GHSA-52cp-r559-cp3m

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm js-yaml 3.15.0, 4.3.0
  • nodeca js-yaml 3.15.0, 4.3.0
  • node-js-yaml Debian 14 4.2.0+~4.0.9-2

debian advisories DEBIAN-CVE-2026-59869

  • receptor ansible automation platform inside 2.5, ansible automation platform developer 2.5, ansible automation platform 2.5 1.6.8-1.el8ap
  • receptor ansible automation platform inside 2.6, ansible automation platform inside 2.5, ansible automation platform developer 2.6 +3 more 1.6.8-1.el9ap
  • python3.12-sqlparse ansible automation platform developer 2.5, ansible automation platform 2.5 0.6.0-1.el8ap
  • python3.12-sqlparse ansible automation platform developer 2.6, ansible automation platform developer 2.5, ansible automation platform 2.6 +1 more 0.6.0-1.el9ap
  • python3.12-gitpython ansible automation platform 2.5 3.1.60-1.el8ap
  • python3.12-gitpython ansible automation platform 2.6, ansible automation platform 2.5 3.1.60-1.el9ap
  • automation-gateway-server ansible automation platform 2.5 2.5.20260923-1.el8ap
  • automation-gateway-server ansible automation platform 2.5 2.5.20260923-1.el9ap

red hat advisories RHSA-2026:71114RHSA-2026:71113RHSA-2026:57590RHSA-2026:40415RHSA-2026:37532RHSA-2026:38304

  • velociraptor openSUSE Tumbleweed 0.76.7.0.git145.b60ef1146-1.1

opensuse advisories openSUSE-SU-2026:12070-1

Is CVE-2026-59869 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-59869 updated cvss 7.5

js-yaml: js-yaml: Denial of Service via crafted YAML documents

  • Red Hat Cryostat 4 grafana-infinity-datasource-npm Red Hat Network Observability Operator network-observability/network-observability-console-plugin-rhel9, network-observability/network-observability-console-plugin-pf5-rhel9 Red Hat Node HealthCheck Operator workload-availability/node-remediation-console-rhel8, workload-availability/node-remediation-console-rhel9, workload-availability/node-healthcheck-rhel9-operator, workload-availability/node-healthcheck-operator-bundle, workload-availability/node-healthcheck-must-gather-rhel9 Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-console-plugin-rhel9, openshift-lightspeed/lightspeed-console-plugin-419-rhel9, openshift-lightspeed/lightspeed-console-plugin-pf5-rhel9 Red Hat OpenShift Pipelines openshift-pipelines/pipelines-hub-ui-rhel8, openshift-pipelines/pipelines-hub-ui-rhel9, openshift-pipelines/pipelines-console-plugin-rhel8, openshift-pipelines/pipelines-console-plugin-rhel9, openshift-pipelines/pipelines-console-plugin-pf5-rhel9
    affected: workaround, no fix available
  • Red Hat Ansible Automation Platform 2 automation-controller, ansible-automation-platform-24/lightspeed-rhel8, ansible-automation-platform-27/mcp-server-rhel9, ansible-automation-platform-tech-preview/mcp-server-rhel9
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat build of Apicurio Registry 3 apicurio/apicurio-registry-ui-rhel8, apicurio/apicurio-registry-ui-rhel9 Red Hat Build of Podman Desktop rh-podman-desktop.git
    affected: workaround, no fix available
  • Red Hat Ceph Storage 9 rhceph/alloy-rhel10
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Connectivity Link 1 rhcl-1/rhcl-console-plugin-rhel9
    affected: workaround, no fix available
  • Red Hat Directory Server 11 389-ds-base Red Hat Directory Server 12 389-ds-base Red Hat Directory Server 13 389-ds-base Red Hat Enterprise Linux 8 grafana, grafana-loki, grafana-mssql, grafana-mysql, grafana-selinux, grafana-graphite, +8 more Red Hat Enterprise Linux 9 grafana, grafana-selinux Red Hat Enterprise Linux 10 grafana
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux AI (RHEL AI) 3 rust, rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/disk-image-cuda-rhel9
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat Hardened Images nodejs20 20.20.2-1.hum1 Red Hat JBoss Enterprise Application Platform 7 js-yaml 3.14.2 Red Hat OpenShift Container Platform 4 openshift4/ose-monitoring-plugin-rhel8
    affected: workaround, no fix planned “Will not fix”
show 18 more
  • Red Hat OpenShift Container Platform 5 openshift5/ose-console-rhel9, openshift5/ose-monitoring-plugin-rhel9, openshift5/nmstate-console-plugin-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift GitOps openshift-gitops-1/argocd-rhel8 Red Hat Single Sign-On 7 js-yaml 3.14.2
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Trusted Artifact Signer rhtas/rhtas-console-ui-rhel9 Red Hat Secrets Management Console for Red Hat OpenShift external-secrets-management/console-plugin-rhel9
    affected: workaround, no fix available
  • Red Hat Cryostat 4 on RHEL 9 cryostat/cryostat-grafana-dashboard-rhel9 4.2.0-14, cryostat/cryostat-openshift-console-plugin-rhel9 4.2.0-14
    fixed: vendor fix RHSA-2026:68333
  • Red Hat multicluster engine for Kubernetes 2.6 multicluster-engine/console-mce-rhel9 1784556108
    fixed: vendor fix RHSA-2026:47949
  • Red Hat multicluster engine for Kubernetes 2.8 multicluster-engine/console-mce-rhel9 1785078604
    fixed: vendor fix RHSA-2026:47735
  • Red Hat multicluster engine for Kubernetes 2.9 multicluster-engine/console-mce-rhel9 1787079359
    fixed: vendor fix RHSA-2026:59559
  • Red Hat multicluster engine for Kubernetes 2.10 multicluster-engine/console-mce-rhel9 1784312384
    fixed: vendor fix RHSA-2026:46885
  • Red Hat multicluster engine for Kubernetes 2.11 multicluster-engine/console-mce-rhel9 1786911977
    fixed: vendor fix RHSA-2026:57194
  • Red Hat multicluster engine for Kubernetes 2.17 multicluster-engine/console-mce-rhel9 1786668856
    fixed: vendor fix RHSA-2026:59593
  • Red Hat Advanced Cluster Management for Kubernetes 2.11 rhacm2/console-rhel9 1787687062
    fixed: vendor fix RHSA-2026:60387
  • Red Hat Advanced Cluster Management for Kubernetes 2.13 rhacm2/console-rhel9 1785078581
    fixed: vendor fix RHSA-2026:47737
  • Red Hat Advanced Cluster Management for Kubernetes 2.14 rhacm2/console-rhel9 1787339248
    fixed: vendor fix RHSA-2026:60388
  • Red Hat Advanced Cluster Management for Kubernetes 2.15 rhacm2/console-rhel9 1784578812
    fixed: vendor fix RHSA-2026:46903
  • Red Hat Advanced Cluster Management for Kubernetes 2.16 rhacm2/console-rhel9 1786908361
    fixed: vendor fix RHSA-2026:57191
  • Red Hat Advanced Cluster Management for Kubernetes 2.17 rhacm2/console-rhel9 1787335105
    fixed: vendor fix RHSA-2026:60386
  • Red Hat Advanced Cluster Security 4.9 advanced-cluster-security/rhacs-main-rhel8 1785413210
    fixed: vendor fix RHSA-2026:48872
  • Red Hat Advanced Cluster Security for Kubernetes 4.11 advanced-cluster-security/rhacs-main-rhel9 1785415868
    fixed: vendor fix RHSA-2026:48891

64 more fixed, 78 more not affected in the full advisory

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
4mo ago

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/nodeca/js-yaml/security/advisories/GHSA-52cp-r559-cp3m referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm js-yaml
>=3.0.0, <3.15.0
>=4.0.0, <4.3.0
3.15.0
4.3.0

Affected products

  • nodeca js-yaml

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of nodeca/js-yaml published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.