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OpenAdvisories
High · 7.5 CVE-2026-48506 EUVD-2026-38388GHSA-vh6j-jc39-fggf

MessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object graph depth

Published Jun 22, 2026 · Updated Jun 23, 2026 · Assigned by GitHub_M

Description

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.

Affected products

VendorProductAffectedFixed
MessagePack-CSharp MessagePack-CSharp >= 3.1.7, < 3.1.7, < 2.5.301 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 python-msgpack No fix yet —

Affected packages

EcosystemPackageAffectedFixedRecord
NuGet MessagePack < 2.5.301 2.5.301 GHSA-vh6j-jc39-fggf
NuGet MessagePack >= 3.0, < 3.1.7 3.1.7 GHSA-vh6j-jc39-fggf

References