CVE Explorer
CVE-2026-48511
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, ExpandoObjectFormatter.Deserialize populates System.Dynamic.ExpandoObject by calling IDictionary<string, object>.Add for each map entry. ExpandoObject internally maintains member names in array-like structures, so inserting many distinct keys can require repeated linear scans and array copies. For large attacker-controlled maps, this produces quadratic CPU and allocation behavior. The issue is especially surprisin
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:dba06b9cf51e9d89cbebcf670f288559112b8b576a51d01c8b51bb4e7390bfe5 · sha256:d1bf6ea4c83a4558… · /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:dba06b9cf51e9d89cbebcf670f288559112b8b576a51d01c8b51bb4e7390bfe5 · sha256:d1bf6ea4c83a4558… · /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:dba06b9cf51e9d89cbebcf670f288559112b8b576a51d01c8b51bb4e7390bfe5 · sha256:d1bf6ea4c83a4558… · /containers/cna/problemTypes/0/descriptions/0
Source references
1 source assertion{"name":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-2x83-8g95-xh59","tags":["x_refsource_CONFIRM"],"url":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-2x83-8g95-xh59"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:dba06b9cf51e9d89cbebcf670f288559112b8b576a51d01c8b51bb4e7390bfe5 · sha256:d1bf6ea4c83a4558… · /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.