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CVE-2026-48502

HIGH
8.2
CVSS 4.0
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.

Metadata

CVE ID
CVE-2026-48502
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-05-21 15:33 UTC
Published
2026-06-22 21:18 UTC
Last updated
2026-06-22 21:18 UTC
Primary CWE
CWE-125
CWE-125: Out-of-bounds Read
Vendor / Product
MessagePack-CSharp / MessagePack-CSharp
Sources
cve.org  ·  NVD

Severity & Metrics

8.2 HIGH CVSS 4.0
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Affected products (1)
VendorProductPlatformVersions
MessagePack-CSharp MessagePack-CSharp — >= 3.1.7, < 3.1.7, < 2.5.301
Weakness (CWE)
CWESourceDescription
CWE-1188 cna CWE-1188: Insecure Default Initialization of Resource
CWE-125 cna CWE-125: Out-of-bounds Read
CWE-190 cna CWE-190: Integer Overflow or Wraparound
CWE-407 cna CWE-407: Inefficient Algorithmic Complexity
CWE-409 cna CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)
CWE-470 cna CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
CWE-502 cna CWE-502: Deserialization of Untrusted Data
CWE-674 cna CWE-674: Uncontrolled Recursion
CWE-789 cna CWE-789: Memory Allocation with Excessive Size Value
CVSS scores (1)
ScoreSeverityVersionSourceVector
8.2 HIGH 4.0 cna CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
References (1)
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