Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 panics when the host reads a component model stream as a different Rust item type than it was created with, because the host-to-host read path asserts matching TypeIds instead of returning an error. Guest code can return a host-created StreamReader<U> that the embedder reads as StreamReader<T>, where both types map to the same component model type, crashing the embedding process.
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-63h4-6cx9-pjfj
Published: 2026-10-29
Updated: 2026-10-29
Base Score: 4.9
Vector: CVSS2#AV:N/AC:H/Au:S/C:N/I:N/A:C
Severity: Medium
Base Score: 4.8
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H
Severity: Medium
Base Score: 5.9
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Severity: Medium
EPSS: 0.00208