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CVE-2026-59869

36
FAUCET Score

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.

First published: Jul 8, 2026Last modified: Jul 8, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 3.0.0, < 3.15.0CPE matchmatch criteria
cpe:2.3:a:nodeca:js-yaml:*:*:*:*:*:node.js:*:*
>= 4.0.0, < 4.3.0CPE matchmatch criteria
cpe:2.3:a:nodeca:js-yaml:*:*:*:*:*:node.js:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.42%
Probability of exploitation in next 30 days
EPSS Percentile
34.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0042 is in the 14th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

npmpatch availablevia ghsa
Product: js-yamlFixed in: 3.15.0
npmpatch availablevia ghsa
Product: js-yamlFixed in: 4.3.0

Vendor Advisories (2)

npmGHSA-52cp-r559-cp3mhigh

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

Jul 20, 2026
microsoft2026-Jul/CVE-2026-59869Important

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

Jul 2, 2026

References

github.com / nodeca/js-yaml/commit/24f13e79ee1343a7e30bd6f6c9d9cdbf0ac9b2b7
Patch
github.com / nodeca/js-yaml/commit/59423c6f8cdc78742ac00e25a4dd39ef16b702e4
Patch
github.com / nodeca/js-yaml/releases/tag/3.15.0
Release Notes
github.com / nodeca/js-yaml/releases/tag/4.3.0
Release Notes
github.com / nodeca/js-yaml/security/advisories/GHSA-52cp-r559-cp3m
ExploitVendor Advisory