MessagePack-CSharp MessagePack for C# up to 2.5.300/3.1.6 MessagePackReader.TrySkip recursion

Summaryinfo

A vulnerability was found in MessagePack-CSharp MessagePack for C# up to 2.5.300/3.1.6. It has been declared as problematic. The affected element is the function MessagePackReader.TrySkip. The manipulation results in recursion. This vulnerability is known as CVE-2026-48506. It is possible to launch the attack remotely. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in MessagePack-CSharp MessagePack for C# up to 2.5.300/3.1.6. It has been classified as problematic. Affected is the function MessagePackReader.TrySkip. The manipulation with an unknown input leads to a recursion vulnerability. CWE is classifying the issue as CWE-674. The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. This is going to have an impact on availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-48506 since 05/21/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 2.5.301 or 3.1.7 eliminates this vulnerability.

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Productinfo

Vendor

• MessagePack-CSharp

Name

• MessagePack for C#

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5.300
• 3.1.0
• 3.1.1
• 3.1.2
• 3.1.3
• 3.1.4
• 3.1.5
• 3.1.6

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