{"id":"CVE-2026-48515","aliases":["GHSA-cxmj-83gh-fp49"],"url":"https://o3.security/vulnerability/CVE-2026-48515","summary":"MessagePack-CSharp: Multi-dimensional array formatters allocate from unchecked dimensions","details":"MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's multi-dimensional array formatters read dimension lengths directly from the payload and allocate T[,], T[,,], or T[,,,] before validating that the dimension product matches the encoded element count. The formatter reads a guarded element array header, but allocation of the target multi-dimensional array happens before the dimensions are checked against that element count. A small payload can therefore declare large dimensions, provide an empty or tiny inner array, and cause a large heap allocation before element data is validated. This vulnerability is fixed in 2.5.301 and 3.1.7.","published":"2026-06-22T21:10:39.110Z","modified":"2026-07-15T01:49:14.474860837Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"NuGet","name":"MessagePack","fixedVersion":"2.5.301"},{"ecosystem":"NuGet","name":"MessagePack","fixedVersion":"3.1.7"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48515.json"},{"type":"ADVISORY","url":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-cxmj-83gh-fp49"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48515"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-15T01:49:14.474860837Z"}}