Vulnerability Description
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's JSON conversion helpers contain multiple recursion paths that do not consistently enforce a depth limit. These paths are in the JSON conversion component rather than normal typed MessagePack deserialization. MessagePackSerializer.ConvertFromJson recursively processes nested JSON arrays and objects in FromJsonCore() without consulting MessagePackSecurity.MaximumObjectGraphDepth. TinyJsonReader.ReadNextToken() recursively consumes comma and colon separator characters, allowing even malformed JSON with long separator runs to consume one stack frame per character. MessagePackSerializer.ConvertToJson applies depth checks to arrays and maps, but the typeless extension branch for ext-100 recursively calls ToJsonCore() without applying MessagePackSecurity.DepthStep(ref reader). Each path can allow attacker-controlled input to exhaust the process stack and trigger an uncatchable StackOverflowException instead of failing with a catchable parse or serialization exception. This vulnerability is fixed in 2.5.301 and 3.1.7.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Messagepack | Messagepack | < 2.5.301 |
Related Weaknesses (CWE)
References
- https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSMitigationVendor Advisory
FAQ
What is CVE-2026-48512?
CVE-2026-48512 is a vulnerability with a CVSS score of 7.5 (HIGH). MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's JSON conversion helpers contain multiple recursion paths that do not consistently enforce a dept...
How severe is CVE-2026-48512?
CVE-2026-48512 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-48512?
Check the references section above for vendor advisories and patch information. Affected products include: Messagepack Messagepack.