CVE Explorer
CVE-2026-48516
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 Thi
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0
Affected products and versions
1 source assertion{"product":"MessagePack-CSharp","vendor":"MessagePack-CSharp","versions":[{"status":"affected","version":">= 3.0, < 3.1.7"},{"status":"affected","version":"< 2.5.301"}]}
- cve_program_cvelist_v5affectedurn:baitaphish:normalized-source-record:v2:f4e634e5abffb581885ce34694a5ddef64f6d5128def89ec04ba2b44c09926e0 · sha256:cd4cf9818c3e2cb2… · /containers/cna/affected/0
Provider-owned CVSS observations
1 source assertion{"metric":{"attackComplexity":"HIGH","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"metric_type":"cvssV4_0"}
- cve_program_cvelist_v5cvssurn:baitaphish:normalized-source-record:v2:f4e634e5abffb581885ce34694a5ddef64f6d5128def89ec04ba2b44c09926e0 · sha256:cd4cf9818c3e2cb2… · /containers/cna/metrics/0/cvssV4_0
CWE assertions
1 source assertion{"cweId":"CWE-407","description":"CWE-407: Inefficient Algorithmic Complexity","lang":"en","type":"CWE"}
- cve_program_cvelist_v5cweurn:baitaphish:normalized-source-record:v2:f4e634e5abffb581885ce34694a5ddef64f6d5128def89ec04ba2b44c09926e0 · sha256:cd4cf9818c3e2cb2… · /containers/cna/problemTypes/0/descriptions/0
Source references
1 source assertion{"name":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-q2h6-ghwm-5qm8","tags":["x_refsource_CONFIRM"],"url":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-q2h6-ghwm-5qm8"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:f4e634e5abffb581885ce34694a5ddef64f6d5128def89ec04ba2b44c09926e0 · sha256:cd4cf9818c3e2cb2… · /containers/cna/references/0
Attribution and limitations
- CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →
Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.