MessagePack's LZ4 decompression may fail with AccessViolationException after dereferencing memory from bad input
Impact
A vulnerability exists in the optional LZ4 decompression path used by MessagePack compression modes Lz4Block and Lz4BlockArray.
The decoder implementation is based on a deprecated fast-decompression algorithm that does not take a source-length bound. A remote attacker can send a crafted MessagePack payload with manipulated LZ4 token/length fields to force out-of-bounds reads from the compressed input buffer. In affected environments, this can trigger an AccessViolationException during decompression, causing process termination (denial of service). Under some conditions, limited unintended memory disclosure from over-read data may also be possible before failure.
This issue affects applications that deserialize untrusted data while LZ4 compression is enabled.
Patches
The v2 versions are patched as of 2.5.301. The v3 versions are patched as of 3.1.7.
Workarounds
Instead of upgrading, an application may take the following precautions:
- Disable LZ4 compression for untrusted input paths (
Lz4Block,Lz4BlockArray). - Only accept compressed payloads from strongly trusted producers.
- Isolate deserialization in a separate process/container with restart supervision to limit availability impact.
Resources
- MESSAGEPACKCSHARP-010
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| .NET (NuGet) | MessagePack | < 2.5.301, >= 3.0.214-rc.1, < 3.1.7 | 2.5.301, 3.1.7 |
Referencias
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H- Debilidad (CWE)
CWE-20- Plataforma
- .NET (NuGet)
- Paquete
MessagePack- Publicada
- 11.06.2026
- Actualizado
- 11.10.2026 11:23
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-hv8m-jj95-wg3x - CC BY 4.0
Historial de vulnerabilidades: MessagePack
Todas las vulnerabilidades publicadas de este paquete (.NET (NuGet)), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 14
- Primera → última
- 01.2020 06.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Alta 3
- Media 11
Divulgaciones por año
- 2020: 1
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 1
- 2025: 0
- 2026: 12
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MessagePack's LZ4 decompression may fail with AccessViolationException after dereferencing memory from bad input esta entrada
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