CVE-2026-107297: CWE-407: Inefficient Algorithmic Complexity in mcollina msgpack5
Description
### Impact The streaming decoder reparses an incomplete container from the beginning whenever another chunk arrives. A remote peer can split one valid MessagePack value across many small chunks, causing quadratic CPU usage and blocking the event loop. ### Patches The decoder now preserves incremental container state so completed elements are not parsed again when more input arrives. ### Workarounds Buffer each complete MessagePack value before decoding it, or limit the number of chunks accepted for a single value.
CVSS v3.1
Score 5.9medium
Affected software
mcollina
msgpack5
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The msgpack5 library's streaming decoder prior to version 6.1.0 suffers from an inefficient algorithmic complexity issue. When decoding streaming data, if an array or map is incomplete, the decoder reparses from the start upon receiving each new chunk. A remote attacker can exploit this by splitting a valid MessagePack container into many small chunks, causing repeated decoding of completed elements. This leads to quadratic CPU consumption and event loop blocking, impacting availability. The vulnerability is fixed in version 6.1.0.
Potential Impact
This vulnerability can cause high CPU usage and block the Node.js event loop, leading to denial of service conditions. There is no impact on confidentiality or integrity. The CVSS score is 5.9 (medium severity) with network attack vector, high attack complexity, no privileges required, no user interaction, and impact limited to availability.
Mitigation Recommendations
Upgrade to msgpack5 version 6.1.0 or later, where this inefficient algorithmic complexity issue is fixed. No other mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-10-07T15:53:23.587Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ac7d1292cdf04f6562ba9af
Added to database: 10/08/2026, 17:21:45 UTC
Last enriched: 10/08/2026, 17:33:47 UTC
Last updated: 10/08/2026, 21:48:50 UTC
Views: 7
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