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HIGH: js-yaml@3.14.2 — Quadratic CPU consumption via merge-key chains (GHSA-52cp-r559-cp3m) #1900

Description

@realfishsam

Vulnerability

Severity: HIGH (CVSS 7.5)
Package: js-yaml@3.14.2
Advisory: GHSA-52cp-r559-cp3m / CVE-2026-59869
Affected component: core
Dependency type: direct (core/package.json devDependencies → "js-yaml": "^3.14.2")

Description

js-yaml's parser is vulnerable to a denial-of-service attack via YAML merge-key chains — "a chain of mappings where each mapping merges the previous one" forces O(N²) computational work during parsing, even though the input document is only linearly sized. A crafted YAML file can cause significant CPU consumption / stalling wherever this dependency parses untrusted YAML.

Fix

Recommended version: js-yaml ≥3.15.0 (or ≥4.3.0 if upgrading the major line)
Fix command:

cd core && npm update js-yaml

core/package.json pins "^3.14.2", which already permits 3.15.0+ without a manifest change.

Risk Assessment

Direct devDependency of core. Need to confirm where js-yaml is actually invoked (e.g. OpenAPI spec loading in core/specs or the SDK generation scripts) — if it only parses first-party YAML files under repo control, exploitability is low. If it's ever used to parse YAML from an external or user-supplied source, this becomes a real DoS vector.


Found by automated dependency vulnerability scan

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