34.0.2

Released 2025-07-18.

Fixed

• Fix a panic in the host caused by preview1 guests using fd_renumber.
  CVE-2025-53901.

• Fix a panic in the preview1 adapter caused by guests using fd_renumber.
  #11277

34.0.1

Released 2025-06-24.

Fixed

• Fix a panic with host-defined tables/globals and concrete reference
  types.
  #11103

33.0.2

Released 2025-07-18.

Fixed

• Fix a panic in the host caused by preview1 guests using fd_renumber.
  CVE-2025-53901.

• Fix a panic in the preview1 adapter caused by guests using fd_renumber.
  #11277

33.0.1

Released 2025-06-24.

Fixed

• Fix a panic with host-defined tables/globals and concrete reference
  types.
  #11103

24.0.4

Released 2025-07-18.

Fixed

• Fix a panic in the host caused by preview1 guests using fd_renumber.
  CVE-2025-53901.

• Fix a panic in the preview1 adapter caused by guests using fd_renumber.
  #11277

24.0.3

Released 2025-06-24.

Fixed

• Fix a panic with host-defined tables/globals and concrete reference
  types.
  #11103

34.0.1

Released 2025-06-24.

Fixed

• Fix a panic with host-defined tables/globals and concrete reference
  types.
  #11103

33.0.1

Released 2025-06-24.

Fixed

• Fix a panic with host-defined tables/globals and concrete reference
  types.
  #11103

32.0.1

Released 2025-06-24.

Fixed

• Fix a panic with host-defined tables/globals and concrete reference
  types.
  #11103

24.0.3

Released 2025-06-24.

Fixed

• Fix a panic with host-defined tables/globals and concrete reference
  types.
  #11103

34.0.0

Released 2025-06-20.

Added

• Support for SIMD in the Pulley interpreter can now be disabled at compile-time
  to shrink the size of the final binary.
  #10727

• The C API now has wasmtime_trap_new_code to create a wasm_trap_t from
  its code.
  #10765

• Winch's support for x86_64 is now classified with tier 1 support in Wasmtime.
  #10755

• Winch's support for aarch64 now implements stack checks to pass many more spec
  tests.
  #10763

• Cranelift's s390x backend now has full support for the f128 type.
  #10774

• Wasmtime's C API for the component model has initial support for calling
  functions.
  #10697
  #10841
  #10858
  #10864
  #10877

• The wasmtime wast command now has a --generate-dwarf flag to show
  filename/line number information for backtraces.
  #10780

Changed

• The shape of bindgen!-generated add_to_linker functions has changed with
  the removal of GetHost and replacement of a HasData trait. For more
  information see the associated PR.
  #10770

• Wasmtime's Store<T> now requires that T: 'static. This is done in
  preparation for merging WASIp3 work to the main repository with some more
  information on the associated PR.
  #10760

• The wasmtime::component::Instance::instance_pre method is now public.
  #10761

• Wasmtime and Cranelift's minimnum supported version of Rust (MSRV) is now
  1.85.0.
  #10785

• Cranelift's debugtrap on aarch64 now generates brk #0xf000 for debuggers
  to recognize it.
  #10813

• The wasi-http implementation no longer generates a trap if the handle to
  receive the response on the host is dropped early.
  #10833

• The wasmtime serve command will now send some boilerplate descriptive HTML
  on a 500 server error instead of nothing.
  #10851

• A significant amount of work has gone into the new assembler for the x64
  backend. Too many PRs to list here but progress continues apace at defining
  all machine instructions in a standalone crate.

• Cranelift will now reject unimplemented big-endian loads/stores on backends
  that do not implement this functionality.
  #10863

• The wasmtime explore generated HTML handles large modules better now.
  #10892

• Wasmtime's internal representation of wasmtime::Func has changed and a
  previous optimization of Func::call has been lost. If affected it'd
  recommended to use Func::call_unchecked instead or to open an issue.
  #10897

33.0.0

Released 2025-05-20.

Added

• Cranelift now has initial support for try_call and try_call_indirect
  instructions, to be used in the future for the WebAssembly exception-handling
  proposal. Wasmtime does not yet implement this proposal yet.
  #10510
  #10557
  #10593

• Cranelift can now optimize some simple possibly-side-effectful instructions,
  such as division.
  #10524

• Wasmtime now supports --invoke for components using the WAVE format.
  #10054

• Initial support for the Component Model has landed in Wasmtime's C API. Note
  that the API is not yet feature-complete, however.
  #10566
  #10598
  #10651
  #10675

• Wasmtime's C++ API is now available from this repository and the
  bytecodealliance/wasmtime-cpp repository has been archived. Additionally the
  monolithic wasmtime.hh header file has been split into separate header
  files.
  #10582
  #10600

• Wasmtime's cookbook-style documentation has been expanded.
  #10630

• Wasmtime's now supports custom yield behavior when using epoch interrupts.
  #10671

Changed

• Wasmtime's bindgen now type-checks export functions in the constructor of
  the generated {Worldname}Pre or {Worldname} structs, rather than at the
  call of the export function.
  #10610

• Wasmtime's component::Component and component::Instance now have consistient
  get_export and get_export_index methods, which return (ComponentItem, ComponentExportIndex) and ComponentExportIndex, respectively.
  #10597

• On failure, wasmtime serve gives an internal server error response, rather
  than closing the connection.
  #10645

• Cranelift's single-pass allocator has been disabled due to being unable to
  support internal refactorings in preparation for the WebAssembly exceptions
  proposal. Re-enabling this allocator is tracked at
  regalloc2#217 for
  those interested.
  #10554

• Wasmtime's {Array,Extern,Struct}Ref functions will now automatically trigger
  a GC.
  #10560

• Wasmtime's GC heaps now use the same translation techniques as linear memories
  meaning they have far fewer bounds-checks than before.
  #10503

• Wasmtime's implementation of WASIp2 has moved to wasmtime_wasi::p2 from the
  root of the crate.
  #10073

• Wasmtime will no longer emit calls to Cranelift-defined "libcalls" and instead
  everything goes through Wasmtime's libcall mechanism instead, paving the way
  for a future change for more efficient stack limit checking in wasm. This can
  also improve deserialize-from-disk times and improve page cache usage for
  modules that use libcalls as relocations are no longer necessary.
  #10657

• Configuration of caching can now be done through an API instead of exclusively
  through a configuration file. Additionally cache-related APIs in Config have
  changed.
  #10665

• Resources in the Component Model are now stored in a single table per-instance
  instead of per-type tables. Guests will see a different pattern of index
  allocation but this is not expected to cause any issues at runtime.
  #10701

Fixed

• Some math intrinsics have been fixed when compiled by Rust 1.87+.
  #10534

• Component model libcalls correctly handle platform-specific argument extension
  in ABIs.
  #10540

• An off-by-one issue with DWARF debuginfo has been fixed.
  #10570

• The Config::target method is no longer gated by a #[cfg] for an enabled
  compiler, it can be used when only the runtime feature is available.
  #10618

• An issue with "simulated" DWARF has been fixed.
  #10681

• C/C++ headers are now tested that they can be included in isolation, and a
  number of issues have been fixed.
  #10694