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CVE-2026-59870: Nodeca Js-Yaml Allocation Without Limits (CVSS 7.5)

CVE-2026-59870 is a high severity allocation without limits in Nodeca Js-Yaml with a CVSS score of 7.5. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Last updated: Oct 6, 2026

Quick answer

Direct answer

CVE-2026-59870 is a high severity allocation without limits in Nodeca Js-Yaml with a CVSS score of 7.5. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Risk scores

CVSS base score
7.5HIGH
EPSS probability
0.74%
Higher than 54 percent of all CVEs
CISA KEV
Not listed
CVSS metricWhat it means
Attack vector (AV:N)Network: reachable remotely
Attack complexity (AC:L)Low complexity
Privileges required (PR:N)No privileges required
User interaction (UI:N)No user interaction
Scope (S:U)Scope unchanged
Confidentiality (C:N)No confidentiality impact
Integrity (I:N)No integrity impact
Availability (A:H)High availability impact

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

About Nodeca Js-Yaml

CVE-2026-59870 affects Nodeca Js-Yaml, a product from Nodeca. Before acting, confirm where Nodeca Js-Yaml runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.

What the flaw is

In plain terms: 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.

The weakness class is Allocation Without Limits. Resources are allocated without a cap.

Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Affected versions and timeline

FieldDetail
ProductNodeca Js-Yaml
Affected versionsJs-Yaml from 5.0.0 before 5.2.1
PublishedJul 8, 2026
Last modifiedOct 6, 2026
Added to CISA KEVNot listed
Assigning CNAsecurity-advisories@github.com

How to detect it

  • Inventory every instance of Nodeca Js-Yaml and record the running version against the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
  • Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.

How to fix it

  • Apply the fixed version of Nodeca Js-Yaml named in the vendor advisory.
  • If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
  • Rescan after the change to prove the exposure is gone, then close the ticket.

CTEM action plan

CTEM stageWhat to do for this CVE
ScopeAdd every business service that depends on Nodeca Js-Yaml to the current CTEM cycle.
DiscoverFind all instances, including shadow and cloud deployments, and record versions and exposure.
PrioritizeRank using EPSS and CVSS together with asset exposure and business impact.
ValidateConfirm the flaw is reachable and exploitable in your environment and that compensating controls work.
MobilizeAssign the fix to the asset owner with a due date matched to the priority, then verify closure.

CWE References

Technical References

Frequently asked questions

CVE-2026-59870 is a high severity allocation without limits in Nodeca Js-Yaml with a CVSS score of 7.5. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

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