CVE-2026-48506: high-severity vulnerability in MessagePack-CSharp
MessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object graph depth
Published · Updated
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.5%
exploitation probability
0.5%top 61% 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, MessagePackReader.TrySkip() recursively descends into nested arrays and maps without incrementing the reader depth or calling the configured depth checks. This bypasses MessagePackSecurity.MaximumObjectGraphDepth, the library's documented protection against deeply nested object graphs. Many generated and dynamic formatters call reader.Skip() when they encounter unknown map keys, unknown array members, ignored fields, or data that should be skipped for forward compatibility. A deeply nested value in one of these skipped positions can therefore cause unbounded recursion and an uncatchable StackOverflowException. This vulnerability is fixed in 2.5.301 and 3.1.7.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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-2026-48502HIGHMessagePack-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%CVE-2026-48512MEDIUMMessagePack-CSharp: JSON conversion APIs can recurse without consistent depth enforcementEPSS 0.4%