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-17660965
- published28 Jun 2026
- disclosed25 Jun 2026
- creditAArnott
Introduced: 25 Jun 2026
NewCVE-2026-48512 (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 JSON conversion process. An attacker can cause the application to exhaust the process stack and terminate unexpectedly by submitting deeply nested JSON arrays or objects, or by providing malformed JSON with long runs of separator characters, which are recursively processed without consistent depth enforcement. This can result in an uncatchable process termination. This is only exploitable if the application processes attacker-controlled JSON or MessagePack payloads using the affected conversion APIs.
Workaround
This vulnerability can be mitigated by validating JSON nesting depth with a parser that enforces depth limits before conversion, rejecting malformed JSON, and applying strict input-size limits. Avoid passing untrusted JSON to the conversion APIs until a patched version is available.