MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter<TKey,TElement> constructs an internal Dictionary<TKey, IGrouping<TKey,TElement>> with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer<TKey>(). This formatter omission allows hash-collision CPU denial of service against ILookup<TKey,TElement> even when the application has opted into the untrusted-data security posture This vulnerability is fixed in 2.5.301 and 3.1.7.
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History
Mon, 22 Jun 2026 22:00:00 +0000
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| Description | MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter<TKey,TElement> constructs an internal Dictionary<TKey, IGrouping<TKey,TElement>> with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer<TKey>(). This formatter omission allows hash-collision CPU denial of service against ILookup<TKey,TElement> even when the application has opted into the untrusted-data security posture This vulnerability is fixed in 2.5.301 and 3.1.7. | |
| Title | MessagePack-CSharp: InterfaceLookupFormatter bypasses collision-resistant comparer settings | |
| Weaknesses | CWE-407 | |
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cvssV4_0
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-06-22T21:09:51.787Z
Reserved: 2026-05-21T16:18:10.619Z
Link: CVE-2026-48516
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
Updated: 2026-06-23T00:30:06Z