CVE-2026-53550: CWE-407: Inefficient Algorithmic Complexity in nodeca js-yaml
js-yaml versions prior to 4.2.0 contain an inefficient algorithmic complexity vulnerability in merge-key processing. A crafted YAML document with repeated aliases in a merge sequence can cause quadratic CPU usage, leading to denial of service by blocking the Node.js event loop. This issue is fixed in version 4.2.0.
AI Analysis
Technical Summary
CVE-2026-53550 describes an algorithmic complexity vulnerability (CWE-407) in the nodeca js-yaml JavaScript YAML parser and dumper. Specifically, before version 4.2.0, processing a crafted YAML document that repeats the same alias many times in a merge sequence (<<) triggers quadratic parse-time behavior in the merge-key handling code within lib/loader.js. This results in CPU exhaustion that can block the Node.js worker/event loop for several seconds with a relatively small payload (tens of KB), causing a denial of service condition. The vulnerability is resolved in js-yaml version 4.2.0.
Potential Impact
An attacker can cause denial of service by submitting a specially crafted YAML document that exploits the quadratic CPU usage in merge-key processing. This leads to blocking of the Node.js event loop for seconds, impacting availability. There is no impact on confidentiality or integrity. The CVSS v3.1 base score is 5.3 (medium severity), reflecting network attack vector, low complexity, no privileges required, no user interaction, and impact limited to availability.
Mitigation Recommendations
Upgrade js-yaml to version 4.2.0 or later, where this vulnerability is fixed. No other mitigation or workaround is indicated. Patch status is confirmed fixed in 4.2.0.
CVE-2026-53550: CWE-407: Inefficient Algorithmic Complexity in nodeca js-yaml
Description
js-yaml versions prior to 4.2.0 contain an inefficient algorithmic complexity vulnerability in merge-key processing. A crafted YAML document with repeated aliases in a merge sequence can cause quadratic CPU usage, leading to denial of service by blocking the Node.js event loop. This issue is fixed in version 4.2.0.
CVSS v3.1
Score 5.3medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-53550 describes an algorithmic complexity vulnerability (CWE-407) in the nodeca js-yaml JavaScript YAML parser and dumper. Specifically, before version 4.2.0, processing a crafted YAML document that repeats the same alias many times in a merge sequence (<<) triggers quadratic parse-time behavior in the merge-key handling code within lib/loader.js. This results in CPU exhaustion that can block the Node.js worker/event loop for several seconds with a relatively small payload (tens of KB), causing a denial of service condition. The vulnerability is resolved in js-yaml version 4.2.0.
Potential Impact
An attacker can cause denial of service by submitting a specially crafted YAML document that exploits the quadratic CPU usage in merge-key processing. This leads to blocking of the Node.js event loop for seconds, impacting availability. There is no impact on confidentiality or integrity. The CVSS v3.1 base score is 5.3 (medium severity), reflecting network attack vector, low complexity, no privileges required, no user interaction, and impact limited to availability.
Mitigation Recommendations
Upgrade js-yaml to version 4.2.0 or later, where this vulnerability is fixed. No other mitigation or workaround is indicated. Patch status is confirmed fixed in 4.2.0.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-09T18:13:07.263Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a39572aeed863c81e05382e
Added to database: 06/22/2026, 15:39:22 UTC
Last enriched: 06/22/2026, 15:57:25 UTC
Last updated: 06/22/2026, 21:51:00 UTC
Views: 6
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