How severe is CVE-2026-59870?

CVE-2026-59870 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-59870 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-59870?

CVE-2026-59870 affects Nodeca Js-yaml. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-59870?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-59870 published?

CVE-2026-59870 was published on 2026-07-08 and last updated on 2026-07-10.

CVE-2026-59870

CVE-2026-59870 is a medium-severity vulnerability in Nodeca Js-yaml with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (34th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Nodeca Js-yaml
Published: 2026-07-08
Last modified: 2026-07-10

Description

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 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. This issue is fixed in version 5.2.1.

Frequently asked questions

What is CVE-2026-59870?: js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 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. This issue is fixed in version 5.2.1.
How severe is CVE-2026-59870?: CVE-2026-59870 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-59870 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-59870?: CVE-2026-59870 affects Nodeca Js-yaml. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-59870?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-59870 published?: CVE-2026-59870 was published on 2026-07-08 and last updated on 2026-07-10.

References

Affected products (1)

cpe:2.3:a:nodeca:js-yaml:*:*:*:*:*:node.js:*:*

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