Answer in brief
CVE-2026-59870 records a High severity (CVSS 7.5) vulnerability in js-yaml quadratic-complexity denial of service via YAML11_SCHEMA !!omap parsing. The current sources do not mark it as known exploited. The current feed maps nodeca/js-yaml (generic), nodeca/js-yaml (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps nodeca/js-yaml (generic), nodeca/js-yaml (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:nodeca:js-yaml:*:*:*:*:*:node.js:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| nodeca/js-yamlgeneric | >=5.0.0 <5.2.1 || >=3.0.0 <3.15.1 || >=4.0.0 <4.3.1 | 5.2.1, 3.15.1, 4.3.1 |
| nodeca/js-yamlgeneric | >=5.0.0 <5.2.1 | 5.2.1 |
Published upstream
Jul 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 8, 2026
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.
Quoted source text, attributed separately from HOL analysis.