Jsonnet Typenamehandling
Json.NET is configured with TypeNameHandling other than None, so type names embedded in the JSON ($type) are used to construct arbitrary CLR types, enabling deserialization RCE on untrusted input (CWE-502).
Standards mapping
- OWASP Top 10
- A08:2021 - Software and Data Integrity Failures
- OWASP ASVS
- V5.5.3 (L1)
Vulnerable vs. safe
TypeNameHandling = TypeNameHandling.AllTypeNameHandling = TypeNameHandling.NoneWhy it matters & how to fix it
Json.NET is configured with TypeNameHandling other than None, so type names embedded in the JSON ($type) are used to construct arbitrary CLR types, enabling deserialization RCE on untrusted input (CWE-502). Set TypeNameHandling.None, or if polymorphism is required, supply a strict SerializationBinder that allow-lists only the expected types.
References
Rule ID integsec.csharp.deserialization.jsonnet-typenamehandling - engine: Opengrep - license: MIT - Copyright (c) IntegSec Inc.
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