Wasmtime is a runtime for WebAssembly. In versions from 38.0.0 to before 38.0.3, the implementation of component-model related host-to-wasm trampolines in Wasmtime contained a bug where it's possible to carefully craft a component, which when called in a specific way, would crash the host with a segfault or assert failure. Wasmtime 38.0.3 has been released and is patched to fix this issue. There are no workarounds.
Exploitability
AV:NAC:HAT:PPR:LUI:PVulnerable System
VC:NVI:NVA:LSubsequent System
SC:NSI:NSA:L2.1/CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:LOther