cbcvebase.
CVE-2023-30624
published 2023-04-27

CVE-2023-30624: Wasmtime is a standalone runtime for WebAssembly. Prior to versions 6.0.2, 7.0.1, and 8.0.1, Wasmtime's implementation of managing per-instance state, such as…

PriorityP351high8.8CVSS 3.1
AVNACLPRLUINSUCHIHAH
EPSS
0.45%
35.9th percentile
Wasmtime is a standalone runtime for WebAssembly. Prior to versions 6.0.2, 7.0.1, and 8.0.1, Wasmtime's implementation of managing per-instance state, such as tables and memories, contains LLVM-level undefined behavior. This undefined behavior was found to cause runtime-level issues when compiled with LLVM 16 which causes some writes, which are critical for correctness, to be optimized away. Vulnerable versions of Wasmtime compiled with Rust 1.70, which is currently in beta, or later are known to have incorrectly compiled functions. Versions of Wasmtime compiled with the current Rust stable release, 1.69, and prior are not known at this time to have any issues, but can theoretically exhibit potential issues. The underlying problem is that Wasmtime's runtime state for an instance involves a Rust-defined structure called `Instance` which has a trailing `VMContext` structure after it. This `VMContext` structure has a runtime-defined layout that is unique per-module. This representation cannot be expressed with safe code in Rust so `unsafe` code is required to maintain this state. The code doing this, however, has methods which take `&self` as an argument but modify data in the `VMContext` part of the allocation. This means that pointers derived from `&self` are mutated. This is typically not allowed, except in the presence of `UnsafeCell`, in Rust. When compiled to LLVM these functions have `noalias readonly` parameters which means it's UB to write through the pointers. Wasmtime's internal representation and management of `VMContext` has been updated to use `&mut self` methods where appropriate. Additionally verification tools for `unsafe` code in Rust, such as `cargo miri`, are planned to be executed on the `main` branch soon to fix any Rust-level issues that may be exploited in future compiler versions. Precomplied binaries available for Wasmtime from GitHub releases have been compiled with at most LLVM 15 so are not known to be vulnerable. As mentioned above, how

Affected

10 ranges
VendorProductVersion rangeFixed in
bytecodealliancewasmtime< 6.0.26.0.2
bytecodealliancewasmtime
bytecodealliancewasmtime
bytecodealliancewasmtime
bytecodealliancewasmtime
bytecodealliancewasmtime>= 0 < 6.0.26.0.2
bytecodealliancewasmtime>= 0.0.0-0 < 6.0.26.0.2
bytecodealliancewasmtime>= 7.0.0 < 7.0.17.0.1
bytecodealliancewasmtime>= 8.0.0 < 8.0.18.0.1
debianrust-wasmtime

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_debian3.9LOW
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