VULNERABILITY INTELLIGENCE

CVE-2026-48502

CVSS score8.2 HIGH
EPSS probability0.44%
CISA KEVNot currently listed
Published2026-06-22
Last modified2026-06-23
CVSS vectorCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Description

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.

Weakness classification

  • 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

Primary references