MessagePack-CSharp MessagePack for C# up to 2.5.300/3.1.6 allocation of resources

Summaryinfo

A vulnerability identified as problematic has been detected in MessagePack-CSharp MessagePack for C# up to 2.5.300/3.1.6. This impacts an unknown function. Performing a manipulation results in allocation of resources. This vulnerability was named CVE-2026-48515. The attack may be initiated remotely. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in MessagePack-CSharp MessagePack for C# up to 2.5.300/3.1.6. This affects some unknown functionality. The manipulation with an unknown input leads to a allocation of resources vulnerability. CWE is classifying the issue as CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. This is going to have an impact on availability. The summary by CVE is:

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's multi-dimensional array formatters read dimension lengths directly from the payload and allocate T[,], T[,,], or T[,,,] before validating that the dimension product matches the encoded element count. The formatter reads a guarded element array header, but allocation of the target multi-dimensional array happens before the dimensions are checked against that element count. A small payload can therefore declare large dimensions, provide an empty or tiny inner array, and cause a large heap allocation before element data is validated. This vulnerability is fixed in 2.5.301 and 3.1.7.

The weakness was presented by Dimensional as GHSA-cxmj-83gh-fp49. It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-48515 since 05/21/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

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

CPE 2.3info

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CPE 2.2info

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