41.0.3

Released 2026-02-04.

Fixed

• Fix an incorrect mid-end optimization rule that could cause a compiler panic
  due to mismatched types.
  #12504

41.0.2

Released 2026-02-03.

Fixed

• Reduce the dependencies of the wasmtime-internal-jit-icache-coherence crate.
  #12446

41.0.1

Released 2026-01-26.

Fixed

• Fixed a bug in lowering of f64.copysign on x86-64 whereby when combined
  with an f64.load, the resulting machine code could read 16 bytes rather
  than 8 bytes. This could result in a segfault when Wasmtime is configured
  without signals-based traps.

40.0.3

Released 2026-01-26.

Fixed

• Fixed a bug in lowering of f64.copysign on x86-64 whereby when combined
  with an f64.load, the resulting machine code could read 16 bytes rather
  than 8 bytes. This could result in a segfault when Wasmtime is configured
  without signals-based traps.

36.0.5

Released 2026-01-26.

Fixed

• Fixed a bug in lowering of f64.copysign on x86-64 whereby when combined
  with an f64.load, the resulting machine code could read 16 bytes rather
  than 8 bytes. This could result in a segfault when Wasmtime is configured
  without signals-based traps.

41.0.0

Released 2026-01-20.

Added

• Support for {Future,Stream}Any in the component model has improved.
  #12142

• Wasmtime has initial support for breakpoints and single-stepping with the
  debug feature for guest programs.
  #12133

• Wasmtime has begun adding a new Error type which is similar to
  anyhow::Error but supports gracefully handling OOM. Wasmtime still uses
  anyhow::Error but this will change in the future to wasmtime::Error which
  will be a distinct type.
  #12163

• An initial top-level crate for async-debugging guest programs has been added.
  #12183

Changed

• Cranelift now optimizes redundant select + icmp instructions.
  #12135

• Synchronous component model functions can no longer block before returning.
  This implements a change in the upstream specification to the upcoming async
  support in the component model which places stricter restrictions on
  non-async functions and their ability to perform blocking operations.
  #12043

• Frame iteration in debug mode now visits all activations which enables
  seeing all frames from recursive wasm calls.
  #12176

• Wasmtime now requires Rust 1.90.0 or later.
  #12167

• Intra-component stream/future reads/writes are now allowed for simple data
  types.
  #12181

• The POLL callback code has been removed from the canonical ABI for async
  functions and the waitable-set.poll function no longer yields.
  #12182

• Guest-to-guest adapters injected by Wasmtime now have improved trapping error
  messages.
  #12215

Fixed

• #[derive(Lift)] for enums with exactly 256 cases has been fixed.
  #12140

• With component-model-async support recursively calling a guest from a host
  function has now been fixed.
  #12152

40.0.2

Released 2026-01-14.

Fixed

• A possible stack overflow in the x64 backend with cmp emission has been
  fixed.
  #12333

• Some ISLE optimization rules which created erroneous IR for vector inputs have
  been fixed.
  #12179
  #12335

• The x64 lowering of shld has been fixed for some edge caxes.
  #12321

39.0.2

Released 2026-01-14.

Fixed

• A possible stack overflow in the x64 backend with cmp emission has been
  fixed.
  #12333

36.0.4

Released 2026-01-14.

Fixed

• A possible stack overflow in the x64 backend with cmp emission has been
  fixed.
  #12333