Wasmtime Files

41.0.4

Released 2026-02-24.

Changed

• Wasmtime's implementation of WASI now has the ability to limit resource consumption on behalf of the guest, such as host-allocated memory. This means that some behaviors previously allowed by Wasmtime can now disallowed, such as transferring excessive data from the guest to the host. Additionally calls to wasi:random/random.get-random-bytes, for example, can have limits in place to avoid allocating too much memory on the host. To preserve backwards-compatible behavior these limits are NOT set by default. Embedders must opt-in to configuring these knobs as appropriate for their embeddings. For more information on this see the related security advisory with further details on knobs added and what behaviors can be restricted. GHSA-852m-cvvp-9p4w

Fixed

• Panics when adding too many headers to a wasi:http/types.fields has been resolved GHSA-243v-98vx-264h

• Panic when dropping a [Typed]Func::call_async future. GHSA-xjhv-v822-pf94