CVE-2026-73643
CVE-2026-73643 · js-yaml: Exponential parsing time in the flow collections leads to denial of service
This page contains facts from public vulnerability sources. Check the original advisory before updating.
js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src/parser/parser.ts, readFlowCollection uses restoreState and calls parseNode a second time when a flow-sequence entry is recognized as a key: value pair. If the key is a nested flow sequence of the same shape, every level is parsed twice, causing O(2^n) work and allowing an input under 200 bytes to keep one CPU busy for minutes, block the Node.js event loop, and stall the process. No anchors, aliases, merges, tags, or nondefault options are required. This issue is fixed in version 5.2.2.
CVSS 7.5 · High · EPSS 0.5% · Fix available
- Published
- Updated
Affected products and versions
js-yaml
- Versions
- >= 5.0.0, < 5.2.2: Affected
No fix published
js-yaml npm
- Affected ranges
- SEMVER: ≥ 5.0.0, < 5.2.2
Update to 5.2.2
node-js-yaml Ubuntu:18.04:LTS
- Versions
- 3.9.1+dfsg-1
- 3.10.0+dfsg-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
node-js-yaml Ubuntu:20.04:LTS
- Versions
- 3.13.1+dfsg-2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
node-js-yaml Ubuntu:22.04:LTS
- Versions
- 3.14.1+dfsg+~3.12.6-2
- 4.1.0+dfsg+~4.0.5-4ubuntu1
- 4.1.0+dfsg+~4.0.5-5
- 4.1.0+dfsg+~4.0.5-6
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
node-js-yaml Ubuntu:24.04:LTS
- Versions
- 4.1.0+dfsg+~4.0.5-7
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
node-js-yaml Ubuntu:26.10
- Versions
- 4.1.1+dfsg+~4.0.9-1
- 4.2.0+~4.0.9-1
- 4.2.0+~4.0.9-2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
node-js-yaml Ubuntu:26.04:LTS
- Versions
- 4.1.0+dfsg+~4.0.5-7
- 4.1.1+dfsg+~4.0.9-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published