CVE-2026-73643: CWE-407: Inefficient Algorithmic Complexity in nodeca js-yaml
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.
AI Analysis
Technical Summary
The js-yaml JavaScript library versions >=5.0.0 <5.2.2 have a vulnerability (CWE-407) where the parser's readFlowCollection function calls parseNode multiple times for nested flow sequences of the same shape, causing exponential parsing time (O(2^n)). This can cause a small YAML input (under 200 bytes) to consume excessive CPU resources, blocking the Node.js event loop and stalling the process. No special YAML constructs are needed to trigger this. The vulnerability is resolved in version 5.2.2.
Potential Impact
Exploitation of this vulnerability results in a denial-of-service condition by causing the Node.js event loop to stall due to excessive CPU consumption during YAML parsing. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade js-yaml to version 5.2.2 or later where this issue is fixed. No other mitigations are indicated. Patch status is confirmed fixed in 5.2.2.
CVE-2026-73643: CWE-407: Inefficient Algorithmic Complexity in nodeca js-yaml
Description
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 v3.1
Score 7.5high
Affected software
nodeca
js-yaml
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The js-yaml JavaScript library versions >=5.0.0 <5.2.2 have a vulnerability (CWE-407) where the parser's readFlowCollection function calls parseNode multiple times for nested flow sequences of the same shape, causing exponential parsing time (O(2^n)). This can cause a small YAML input (under 200 bytes) to consume excessive CPU resources, blocking the Node.js event loop and stalling the process. No special YAML constructs are needed to trigger this. The vulnerability is resolved in version 5.2.2.
Potential Impact
Exploitation of this vulnerability results in a denial-of-service condition by causing the Node.js event loop to stall due to excessive CPU consumption during YAML parsing. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade js-yaml to version 5.2.2 or later where this issue is fixed. No other mitigations are indicated. Patch status is confirmed fixed in 5.2.2.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-13T14:04:09.603Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a7e08efbf8831d5399b799c
Added to database: 08/13/2026, 18:11:59 UTC
Last enriched: 08/13/2026, 18:26:31 UTC
Last updated: 09/28/2026, 17:57:42 UTC
Views: 75
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