PT-2026-51394 · Messagepack Csharp · Messagepack-Csharp

Published 2026-06-22 · Updated 2026-06-22 · CVE-2026-48510

Mitre

CVSS v4.0

6.3

Medium

Base vector

AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, when MessagePack-CSharp decompresses Lz4Block or Lz4BlockArray payloads, it reads declared uncompressed lengths from the wire and allocates output buffers based on those lengths before validating that the compressed data is valid or that the declared expansion is reasonable. A small payload can claim a very large uncompressed length and force a large allocation before LZ4 decoding begins. This vulnerability is fixed in 2.5.301 and 3.1.7.

Fix

Allocation of Resources Without Limits

Weakness Enumeration

CWE-770

CWE-409

Related Identifiers

CVE-2026-48510

Affected Products

Messagepack-Csharp

References · 2

• https://nvd.nist.gov/vuln/detail/CVE-2026-48510 · Security Note
• https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-v72x-2h86-7f8m · Note