CVE-2022-39394: Bytecodealliance Wasmtime

Critical severity, CVSS 9.8. EPSS: 0.3% chance of exploitation in the next 30 days.

Wasmtime is a standalone runtime for WebAssembly. Prior to version 2.0.2, there is a bug in Wasmtime's C API implementation where the definition of the `wasmtime_trap_code` does not match its declared signature in the `wasmtime/trap.h` header file. This discrepancy causes the function implementation to perform a 4-byte write into a 1-byte buffer provided by the caller. This can lead to three zero bytes being written beyond the 1-byte location provided by the caller. This bug has been patched and users should upgrade to Wasmtime 2.0.2. This bug can be worked around by providing a 4-byte buffer casted to a 1-byte buffer when calling `wasmtime_trap_code`. Users of the `wasmtime` crate are not affected by this issue, only users of the C API function `wasmtime_trap_code` are affected.

Affected products

• Bytecodealliance Wasmtime: before 1.0.2 (fixed in 1.0.2); from 2.0.0, before 2.0.2 (fixed in 2.0.2)

Published 2022-11-10. Last modified 2026-06-17.