Description

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, UnsafeBlitFormatterBase.Deserialize reads an attacker-controlled byteLength from an extension payload and allocates an array based on that value before validating it against the extension header length or remaining payload bytes. The outer extension header is bounded by available input, but that bound is not used to constrain the inner byteLength before allocation. A very small payload can therefore request a very large T[] allocation. This vulnerability is fixed in 2.5.301 and 3.1.7.

Severity (CVSS)

Base score6.3
SeverityMedium
VersionCVSS 4.0
VectorCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Provided byCNA

Weaknesses

  • CWE-770 — CWE-770: Allocation of Resources Without Limits or Throttling

Affected products

VendorProductVersions
MessagePack-CSharpMessagePack-CSharp>= 3.1.7, < 3.1.7; < 2.5.301

References

Authoritative sources

This page is a snapshot. For the latest enrichment and updates, view the record on CVE.org or the NVD.

Generated from the official CVE List on 23 Jun 2026 10:05 UTC.