CVE-2026-59869: CWE-407: Inefficient Algorithmic Complexity in nodeca js-yaml
js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 before 3.15.0 and from 4.0.0 before 4.3.0, js-yaml can spend quadratic CPU time parsing a document whose size grows only linearly when a chain of mappings uses merge keys where each mapping merges the previous one. This issue is fixed in versions 3.15.0 and 4.3.0.
AI Analysis
Technical Summary
The vulnerability in js-yaml (CVE-2026-59869) is an inefficient algorithmic complexity issue (CWE-407) affecting versions >=3.0.0 <3.15.0 and >=4.0.0 <4.3.0. When parsing YAML documents that contain a chain of mappings using merge keys where each mapping merges the previous one, the CPU time required grows quadratically relative to the document size, which itself grows linearly. This can lead to performance degradation or denial of service due to excessive CPU consumption. The vulnerability has been addressed in versions 3.15.0 and 4.3.0.
Potential Impact
An attacker can craft a YAML document that triggers quadratic CPU time consumption during parsing, potentially causing denial of service by exhausting CPU resources. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade js-yaml to version 3.15.0 or later, or 4.3.0 or later, where this vulnerability is fixed. No other mitigations are indicated. Patch status is confirmed by the version ranges fixed in the description.
CVE-2026-59869: CWE-407: Inefficient Algorithmic Complexity in nodeca js-yaml
Description
js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 before 3.15.0 and from 4.0.0 before 4.3.0, js-yaml can spend quadratic CPU time parsing a document whose size grows only linearly when a chain of mappings uses merge keys where each mapping merges the previous one. This issue is fixed in versions 3.15.0 and 4.3.0.
CVSS v3.1
Score 7.5high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in js-yaml (CVE-2026-59869) is an inefficient algorithmic complexity issue (CWE-407) affecting versions >=3.0.0 <3.15.0 and >=4.0.0 <4.3.0. When parsing YAML documents that contain a chain of mappings using merge keys where each mapping merges the previous one, the CPU time required grows quadratically relative to the document size, which itself grows linearly. This can lead to performance degradation or denial of service due to excessive CPU consumption. The vulnerability has been addressed in versions 3.15.0 and 4.3.0.
Potential Impact
An attacker can craft a YAML document that triggers quadratic CPU time consumption during parsing, potentially causing denial of service by exhausting CPU resources. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade js-yaml to version 3.15.0 or later, or 4.3.0 or later, where this vulnerability is fixed. No other mitigations are indicated. Patch status is confirmed by the version ranges fixed in the description.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-07T15:41:53.607Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4e73c2c9d9e3dbe36042b4
Added to database: 07/08/2026, 15:58:58 UTC
Last enriched: 07/16/2026, 10:06:47 UTC
Last updated: 08/22/2026, 22:52:15 UTC
Views: 275
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