CVE Explorer
CVE-2026-48509
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, the parameterless MessagePackInputFormatter() constructor uses default serializer options, which resolve to MessagePackSerializerOptions.Standard with MessagePackSecurity.TrustedData. The formatter is designed for ASP.NET Core MVC request bodies, which commonly cross an HTTP trust boundary. This insecure default can expose applications to denial-of-service attacks that MessagePackSecurity.UntrustedData is intended
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:f69092f5afa1ce376c754c818265346eaf9272fe01175550d1241e54ef0573dd · sha256:f495b2b2512ec733… · /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:L/VA:L/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW"},"metric_type":"cvssV4_0"}
- cve_program_cvelist_v5cvssurn:baitaphish:normalized-source-record:v2:f69092f5afa1ce376c754c818265346eaf9272fe01175550d1241e54ef0573dd · sha256:f495b2b2512ec733… · /containers/cna/metrics/0/cvssV4_0
CWE assertions
1 source assertion{"cweId":"CWE-1188","description":"CWE-1188: Insecure Default Initialization of Resource","lang":"en","type":"CWE"}
- cve_program_cvelist_v5cweurn:baitaphish:normalized-source-record:v2:f69092f5afa1ce376c754c818265346eaf9272fe01175550d1241e54ef0573dd · sha256:f495b2b2512ec733… · /containers/cna/problemTypes/0/descriptions/0
Source references
1 source assertion{"name":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-2f33-pr97-265q","tags":["x_refsource_CONFIRM"],"url":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-2f33-pr97-265q"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:f69092f5afa1ce376c754c818265346eaf9272fe01175550d1241e54ef0573dd · sha256:f495b2b2512ec733… · /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.