CVE-2026-48515

Name of the Vulnerable Software and Affected Versions MessagePack for C# versions prior to 2.5.301 MessagePack for C# versions prior to 3.1.7

Description 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. Because the allocation of the target multi-dimensional array occurs before the dimensions are checked against the guarded element array header, a small payload can declare large dimensions and provide a tiny or empty inner array, leading to a large heap allocation before element data is validated.

Recommendations Update to version 2.5.301. Update to version 3.1.7.