35.0.0

Released 2025-07-22.

Added

• A new InputFile type has been added for specifying stdin as a file in WASI.
  #10968

• Conditional branches to unconditional traps are now translated to conditional
  traps during legalization.
  #10988

• The TE HTTP header can now be specified by guests.
  #11002

• Winch on AArch64 should now pass all WebAssembly MVP tests. Note that it is
  still not yet Tier 1 at this time, however.
  #10829
  #11013
  #11031
  #11051

• The x64 backend now has lowering rules for {add,sub,or,and} mem, imm
  #11043

• Initial support for WASIp2 in the C API has started to land.
  #11055
  #11172

• Initial support for GC support in the component model has started to land
  (note that it is not finished yet).
  #10967
  #11020

• The wasmtime-wasi-nn crate now has a feature to use a custom ONNX runtime.
  #11060

• Cranelift now optimizes division-by-constant operations to no longer use
  division.
  #11129

• A native-tls backend has been added for the wasi-tls implementation.
  #11064

Changed

• Many more instructions for the x64 backend in Cranelift were migrated to the
  new assembler.
  #10927
  #10928
  #10918
  #10946
  #10954
  #10958
  #10971
  #10942
  #10975
  #11017
  #10898
  #10836
  ... (and more)

• Wasmtime internally uses Pin for VM data structures to make the internal
  implementations more sound to use. This has no effect on the public API of
  Wasmtime.
  #10934
  #10937
  #10943
  #10959
  #11042

• Fused adapters between components now transfer the enum component model type
  more efficiently.
  #10939

• Filenames of --emit-clif now match the symbol names found in *.cwasm
  artifacts and include the function name as well.
  #10947
  #11040

• Wasmtime-internal crates are now all named wasmtime-internal-* to even
  further discourage their use.
  #10963

• Codegen of conditional traps with float compares has been improved.
  #10966

• More patterns are now optimized in ISLE mid-end rules.
  #10978
  #10979
  #11173

• Winch's support for constants/scratch registers has been improved internally.
  #10986
  #10998

• The C API artifacts on Windows are now produced with Clang instead of
  cl.exe.
  #10890

• WebAssembly operand types are now taken into account during translation to
  optimize codegen better in the face of subtyping.
  #11030

• The behavior of blocking-write-and-flush has been updated during flushing
  when closed is found.
  #11018

• WASI WITs have been updated to 0.2.6.
  #11049

• OpenVINO has been updated to v2025.1.
  #11054

• The size of the wasmtime.addrmap section in *.cwasm artifacts has been
  shrunk slightly.
  #11126

• Authorities in wasmtime-wasi-http can now contain the : character.
  #11145

• Wasmtime now requires Rust 1.86 to compile.
  #11142

• Wasmtime's DRC collector has been optimized and has a new more efficient means
  of managing the set of over-approximated roots on the stack.
  #11144
  #11148
  #11167
  #11168
  #11169
  #11175

• The ComponentType trait in Wasmtime now requires the Send and Sync
  bounds for all implementors.
  #11160

• The V128 type is now usable on platforms other than aarch64 and x86_64.
  #11165

• Wasmtime's policy on unsafe code and guidelines has been added.
  #11177

• The std crate will no longer implicitly be used on cfg(unix) and
  cfg(windows) targets when the std Cargo feature is disabled. This means
  that these platforms now require std to be enabled to use the
  platform-specific implementation of linear memory, for example.
  #11152

Fixed

• A panic when optimizing icmp with vectors has been fixed.
  #10948

• A panic when lowering scalar_to_vector with i16x8 types has been fixed.
  #10949

• The vector state register is now considered clobbered by calls on riscv64 to
  ensure it's updated across calls.
  #11048

• An instance of gdb crashing on DWARF emitted by Wasmtime has been fixed.
  #11077

• 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

34.0.2

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