CVE-2026-48514: medium-severity vulnerability in MessagePack-CSharp
MessagePack-CSharp: Unity unsafe blit formatter allocates from unbounded byte length
Published · Updated
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.3epss 0.4%
exploitation probability
0.4%top 67% of all CVEs
observed exploitation
nono source reports it
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, UnsafeBlitFormatterBase<T>.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.
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Affected products
MessagePack-CSharp · MessagePack-CSharpRelated CVEs — MessagePack-CSharp
In the same product, most dangerous first.
CVE-2026-48109HIGHMessagePack-CSharp: LZ4 decompression may fail with AccessViolationException after dereferencing memory from bad inputEPSS 0.5%CVE-2026-48506HIGHMessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object graph depthEPSS 0.5%CVE-2026-48502HIGHMessagePack-CSharp: Denial of service vulnerabilities can swamp the CPU or crash the process with stack and heap overflowsEPSS 0.4%CVE-2026-48509MEDIUMMessagePack-CSharp: ASP.NET Core MessagePackInputFormatter defaults to TrustedData for HTTP request bodiesEPSS 0.4%CVE-2026-48510MEDIUMMessagePack-CSharp: LZ4 decompression allocates from unbounded declared output lengthsEPSS 0.4%CVE-2026-48511MEDIUMMessagePack-CSharp: ExpandoObject formatter can perform quadratic insertion work on untrusted mapsEPSS 0.4%