Uncontrolled Recursion Affecting messagepack package, versions [,2.5.301)[3.0,3.1.7)
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-17660964
- published28 Jun 2026
- disclosed25 Jun 2026
- creditAArnott
Introduced: 25 Jun 2026
NewCVE-2026-48506 (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 Uncontrolled Recursion in the Skip process. An attacker can cause the application to terminate unexpectedly by submitting specially crafted MessagePack payloads containing deeply nested arrays or maps, leading to unbounded recursion and stack exhaustion. This is only exploitable if the application deserializes untrusted MessagePack data and the deserialization process encounters unknown or ignored fields that are skipped.
Workaround
This vulnerability can be mitigated by reducing accepted message sizes or performing strict schema validation outside the affected library to reject unknown or skipped fields before deserialization, although these measures do not fully eliminate the risk.