wasmtime_trap_code C API function has out of bounds write vulnerability

### Impact 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. ### Patches This bug has been patched and users should upgrade to Wasmtime 2.0.2. ### Workarounds This 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. ### References * [Definition of `wasmtime_trap_code`](https://docs.wasmtime.dev/c-api/trap_8h.html#a6580f4f209d3eaebb6e8b9a901a30b7a) * [Mailing list announcement](https://groups.google.com/a/bytecodealliance.org/g/sec-announce/c/c1HBDDJwNPA) * [Patch to fix for `main` branch](https://github.com/bytecodealliance/wasmtime/commit/5b6d5e78de106503b3b9add218bb3d2b1d63c493) ### For more information If you have any questions or comments about this advisory: * Reach out to us on [the Bytecode Alliance Zulip chat](https://bytecodealliance.zulipchat.com/#narrow/stream/217126-wasmtime) * Open an issue in [the bytecodealliance/wasmtime repository](https://github.com/bytecodealliance/wasmtime/)

Source published

1 Feb 2024 00:15:47 UTC

Source modified

2 May 2025 12:51:45 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L

Publisher rating · LOW