CVE-2026-34942
Description
Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of transcoding strings into the Component Model's utf16 or latin1+utf16 encodings improperly verified the alignment of reallocated strings. This meant that unaligned pointers could be passed to the host for transcoding which would trigger a host panic. This panic is possible to trigger from malicious guests which transfer very specific strings across components with specific addresses. Host panics are considered a DoS vector in Wasmtime as the panic conditions are controlled by the guest in this situation. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.
How to fix
- bytecodealliance wasmtime24.0.7, 36.0.7, 42.0.2, 43.0.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| bytecodealliance wasmtime | v < 24.0.7, 25.0.0 ≤ v < 36.0.7, 37.0.0 ≤ v < 42.0.2, 43.0.0 ≤ v < 43.0.1 | 24.0.7, 36.0.7, 42.0.2, 43.0.1 |
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