Out-of-bounds Read Affecting messagepack package, versions [,2.5.301)[3.0.54-alpha,3.1.7)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DOTNET-MESSAGEPACK-17318029
- published12 Jun 2026
- disclosed11 Jun 2026
- creditUnknown
Introduced: 11 Jun 2026
NewCVE-2026-48109 (opens in a new tab)How to fix?
Upgrade MessagePack to version 2.5.301, 3.1.7 or higher.
Overview
MessagePack is a MessagePack(MsgPack) Serializer for C#(.NET, .NET Core, Unity, Xamarin).
Affected versions of this package are vulnerable to Out-of-bounds Read in the LZ4 decompression path for Lz4Block and Lz4BlockArray modes. An attacker can cause process termination or potentially access unintended memory contents by submitting a specially crafted payload with manipulated LZ4 token or length fields.
Workaround
This vulnerability can be mitigated by disabling LZ4 compression for untrusted input paths, only accepting compressed payloads from strongly trusted producers, or isolating deserialization in a separate process or container with restart supervision.