CVE-2026-48502

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePackReader.ReadDateTime() can allocate stack memory based on an attacker-controlled MessagePack extension length. In the slow path for timestamp extension parsing, the computed tokenSize includes the extension body length from the wire and is used in a stackalloc operation before the extension length is validated as one of the valid timestamp sizes. A very small payload can claim a large timestamp extension body and cause a stack allocation large enough to trigger an uncatchable StackOverflowException, terminating the host process. This vulnerability is fixed in 2.5.301 and 3.1.7.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-382j-8mxh-c7x2	Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:messagepack:messagepack::::::c\#::*
	cpe:2.3:a:messagepack:messagepack::::::c\#::*

History

No history.

Information

Published : 2026-06-22 22:16

Updated : 2026-06-23 17:25

NVD link : CVE-2026-48502

Mitre link : CVE-2026-48502

CVE.ORG link : CVE-2026-48502

JSON object : View

Products Affected

messagepack

messagepack

CWE

CWE-125

Out-of-bounds Read

CWE-190

Integer Overflow or Wraparound

CWE-407

Inefficient Algorithmic Complexity

CWE-409

Improper Handling of Highly Compressed Data (Data Amplification)

CWE-470

Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')

CWE-502

Deserialization of Untrusted Data

CWE-674

Uncontrolled Recursion

CWE-789

Memory Allocation with Excessive Size Value

CWE-1188

Initialization of a Resource with an Insecure Default

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