CVE-2026-53550: js-yaml is a JavaScript YAML parser and dumper. Prior to 4.2.0 and 3.15.0, a crafted YAML document can trigger algorithm…
js-yaml is a JavaScript YAML parser and dumper. Prior to 4.2.0 and 3.15.0, a crafted YAML document can trigger algorithmic CPU exhaustion in js-yaml merge-key processing (<<) by repeating the same alias many times in a merge sequence. This causes quadratic parse-time behavior relative to input size and can block a Node.js worker/event loop for seconds with a relatively small payload (tens of KB), resulting in denial of service. The issue is in merge handling inside lib/loader.js. This vulnerability is fixed in 4.2.0 and 3.15.0.
- Published by source
- 2026-06-22
- First seen by Reality Radar
- 2026-10-26
- Last verified
- 2026-10-26
Affected
- Manufacturer
- nodeca
- Products
- js-yaml
- Versions
- <3.15.0 <4.2.0
- CPE
- cpe:2.3:a:nodeca:js-yaml:*:*:*:*:*:node.js:*:*
Whether your exact unit is affected depends on the model, serial number and region in the official notice.
What the official notice says
Risk: CVSS 5.3
Is this affecting you?
Add what you own or use and Reality Radar will tell you when official changes match it — with evidence and next steps.
Sources
- NIST National Vulnerability Database Tier A · official published 2026-06-22
Evidence ledger
Every piece of evidence we store is appended to a public hash chain, so later edits are detectable. Anyone can re-verify it.
| Entry | Kind | Observed | Evidence hash | Entry hash |
|---|---|---|---|---|
| #1729 | new | 2026-10-26 | 66b5fe9b748c…bd8413 | 429abd95813b…e677ff |
Chain head: #1771 9d8a5938d304…171807