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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
Low
Partial disruption
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 2
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Nodeca Js-Yaml
cpe:2.3:a:nodeca:js-yaml:*:*:*:*:*:node.js:*:*
|
— |
3.15.0
|
|
Nodeca Js-Yaml
cpe:2.3:a:nodeca:js-yaml:*:*:*:*:*:node.js:*:*
|
4.0.0
|
4.2.0
|