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CVE-2026-59870

Nodeca Js-yaml denial of service

7.5 HIGHPublic exploitEPSS 0.74%
  1. Published8 Jul 2026

Description

js-yaml is a JavaScript YAML parser and dumper. Prior to 3.15.1, 4.3.1, and 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. In v3 and v4, !!omap is active and exploitable by default. v5 doesn't use !!omap by default, and the chances of activating it are very low.This issue is fixed in 3.15.1, 4.3.1, and 5.2.1.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Nodeca Js-yaml≥ 5.0.0 < 5.2.1

Remediation

Fixed in
Nodeca Js-yaml≥ 5.2.1

References

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Frequently asked

Is CVE-2026-59870 being actively exploited?

CVE-2026-59870 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.74%.

How severe is CVE-2026-59870?

CVE-2026-59870 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.74% probability of exploitation.

Which products are affected by CVE-2026-59870?

Affected products include Nodeca Js-yaml.

How do I fix CVE-2026-59870?

Upgrade affected software to a fixed version, for example Nodeca Js-yaml 5.2.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-59870 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.