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HIGH

CVE-2026-73643

CVSS v3

7.5

HIGH

EPSS Score

0.5 %

exploit probability, as of 2026-10-17

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • js-yamlnpmfrom 5.0.0 · fixed in 5.2.2

Vendor advisories

  • CVE-2026-73643 Red Hat Product Security59 products fixed · 37 known affected

    js-yaml: js-yaml: Denial of Service via exponential parsing in flow collections

    workload-availability/node-healthcheck-must-gather-rhel9 as a component of Node HealthCheck Operator · workload-availability/node-healthcheck-operator-bundle as a component of Node HealthCheck Operator · workload-availability/node-healthcheck-rhel9-operator as a component of Node HealthCheck Operator

  • RHSA-2026:83598 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: RHTAS 1.4.4 - Red Hat Trusted Artifact Signer Release

  • RHSA-2026:70618 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.18.56 security and extras update

  • RHSA-2026:70588 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.17.58 security and extras update

  • RHSA-2026:68681 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Migration Toolkit for Containers (MTC) 1.8.17 update

  • RHSA-2026:68254 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: Red Hat Edge Manager Version 1.2.1 Security Update

11 more advisories

Full record on NVD

Description

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src/parser/parser.ts, readFlowCollection uses restoreState and calls parseNode a second time when a flow-sequence entry is recognized as a key: value pair. If the key is a nested flow sequence of the same shape, every level is parsed twice, causing O(2^n) work and allowing an input under 200 bytes to keep one CPU busy for minutes, block the Node.js event loop, and stall the process. No anchors, aliases, merges, tags, or nondefault options are required. This issue is fixed in version 5.2.2.

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2026-08-13
Last Modified
2026-08-14

Frequently asked questions

What is CVE-2026-73643?

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src/parser/parser.ts, readFlowCollection uses restoreState and calls parseNode a second time when a flow-sequence entry is recognized as a key: value pair. If the key is a nested flow sequence of the same shape, every level is parsed twice, causing O(2^n) work and allowing an input under 200 bytes to keep one CPU busy for minutes, block the Node.js event loop, and stall the process. No anchors, aliases, merges, tags, or nondefault options are required. This issue is fixed in version 5.2.2.

Is CVE-2026-73643 actively exploited?

Active exploitation of CVE-2026-73643 has not been confirmed. Its EPSS score was 0.5% on 2026-10-17, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-73643?

CVE-2026-73643 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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