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CVE-2026-48517— MessagePack-CSharp: Typeless deserialization type restrictions do not recurse into arrays or generic arguments

Quick assessment

Affected
MessagePack-CSharp MessagePack-CSharp
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

MessagePack-CSharp MessagePack-CSharp是MessagePack-CSharp团队的一款消息序列化工具。 MessagePack-CSharp 2.5.301之前版本和3.1.7之前版本存在安全漏洞，该漏洞源于无类型反序列化操作中未递归检查数组元素类型或泛型类型参数，导致被屏蔽的危险类型可以通过数组或构造的泛型类型绕过安全检查。

AI Predicted 7.5 Difficulty: Moderate EPSS 0.35% · P26

Affected Version Matrix 2

VendorProduct Version RangeStatus
MessagePack-CSharp MessagePack-CSharp >= 3.0, < 3.1.7 affected
< 2.5.301 affected
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I. Basic Information for CVE-2026-48517

Vulnerability Information
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Vulnerability Title
MessagePack-CSharp: Typeless deserialization type restrictions do not recurse into arrays or generic arguments
Source: CVE Program / CVE List V5
Vulnerability Description
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's typeless deserialization includes MessagePackSerializerOptions.ThrowIfDeserializingTypeIsDisallowed(Type) as a safety check for dangerous types. The default implementation checks the outer type name, but it does not recursively inspect array element types or generic type arguments. As a result, a type that would be blocked directly can be wrapped inside an array or constructed generic type and pass the outer type check. The formatter machinery can then materialize formatters for the inner blocked type. This vulnerability is fixed in 2.5.301 and 3.1.7.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用外部可控制的输入来选择类或代码(不安全的反射)
Source: CVE Program / CVE List V5
Vulnerability Title
MessagePack-CSharp 代码注入漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MessagePack-CSharp MessagePack-CSharp是MessagePack-CSharp团队的一款消息序列化工具。 MessagePack-CSharp 2.5.301之前版本和3.1.7之前版本存在安全漏洞，该漏洞源于无类型反序列化操作中未递归检查数组元素类型或泛型类型参数，导致被屏蔽的危险类型可以通过数组或构造的泛型类型绕过安全检查。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
MessagePack-CSharp MessagePack-CSharp >= 3.0, < 3.1.7 -

II. Public POCs for CVE-2026-48517

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III. Intelligence Information for CVE-2026-48517

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Vendor Advisories for CVE-2026-48517 (1)

Same Patch Batch · MessagePack-CSharp · 2026-06-22 · 12 CVEs total

CVE-2026-48109 8.2 HIGH MessagePack-CSharp: LZ4 decompression may fail with AccessViolationException after derefer
CVE-2026-48506 7.5 HIGH MessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object gr
CVE-2026-48516 MessagePack-CSharp: InterfaceLookupFormatter bypasses collision-resistant comparer setting
CVE-2026-48511 MessagePack-CSharp: ExpandoObject formatter can perform quadratic insertion work on untrus
CVE-2026-48513 MessagePack-CSharp: DynamicUnionResolver generated deserializers miss depth enforcement
CVE-2026-48512 MessagePack-CSharp: JSON conversion APIs can recurse without consistent depth enforcement
CVE-2026-48502 MessagePack-CSharp: Denial of service vulnerabilities can swamp the CPU or crash the proce
CVE-2026-48509 MessagePack-CSharp: ASP.NET Core MessagePackInputFormatter defaults to TrustedData for HTT
CVE-2026-48510 MessagePack-CSharp: LZ4 decompression allocates from unbounded declared output lengths
CVE-2026-48515 MessagePack-CSharp: Multi-dimensional array formatters allocate from unchecked dimensions
CVE-2026-48514 MessagePack-CSharp: Unity unsafe blit formatter allocates from unbounded byte length

IV. Related Vulnerabilities

Same product: MessagePack-CSharp
Same vendor: MessagePack-CSharp
Same weakness: CWE-470

V. Comments for CVE-2026-48517

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