CVE-2026-48517
CVE-2026-48517 is a high-severity vulnerability in Messagepack with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-470.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- CVSS v4: 6.3
- EPSS exploit prediction: 0% (16th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-38363
- Weakness: CWE-470
- Affected product: Messagepack
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-48517?
- 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.
- How severe is CVE-2026-48517?
- CVE-2026-48517 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
- Is CVE-2026-48517 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-48517?
- CVE-2026-48517 affects Messagepack. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-48517?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-48517 have an EU (EUVD) identifier?
- Yes. CVE-2026-48517 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38363.
- When was CVE-2026-48517 published?
- CVE-2026-48517 was published on 2026-06-22 and last updated on 2026-06-25.
References
Affected products (1)
- cpe:2.3:a:messagepack:messagepack:*:*:*:*:*:c\#:*:*
More vulnerabilities in Messagepack
- CVE-2026-48509 — Critical (CVSS 9.1): MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, the parameterless…
- CVE-2026-48109 — High (CVSS 8.2): MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, A vulnerability exists in the…
- CVE-2026-48516 — High (CVSS 7.5): MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7,…
- CVE-2026-48515 — High (CVSS 7.5): MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's…
- CVE-2026-48514 — High (CVSS 7.5): MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7,…
- CVE-2026-48513 — High (CVSS 7.5): MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, runtime-generated union…
All CVEs affecting Messagepack →
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