bytecodealliance/wasmtime v44.0.0

on GitHub

44.0.0

Released 2026-04-20.

Added

• The wasmtime CLI now supports a -g flag which runs a built-in wasm program
  to host a gdbstub-compatible server (can be connected to with LLDB) to debug
  guest programs.
  #12756
  #12771
  #12856
  #12859

• Wasmtime now has experimental support for the map<K, V> type in the
  component model.
  #12216

• Wasmtime's C API now supports wasm tag types.
  #12763
  #12803

• Wasmtime's C API now supports exceptions.
  #12861

• Wasmtime's C API has more support for the GC proposal.
  #12914
  #12915
  #12916
  #12917

• An initial implementation of the wasi:tls proposal for the 0.3.0-draft
  version has been added.
  #12834

Changed

• The demangle Cargo feature of the wasmtime crate is now compatible with
  no_std targets.
  #12740

• The wasmtime-wasi-tls-* crates are now merged into one crate with feature
  flags for each backend.
  #12780

• Wasmtime now requires Rust 1.92.0 or later to build.
  #12828

• The cranelift-codegen crate now compiles for no_std targets.
  #12812

• The csdb instruction, a defense-in-depth measure for spectre, is no longer
  emitted by default on aarch64 to match what peer runtimes are doing. In some
  situations this is known to provide up to a 6x performance boost on macOS as
  well.
  #12932

Fixed

• Wasmtime's native DWARF has been improved on aarch64 to support recovering
  values more frequently.
  #12779

• A significant number of minor issues have been fixed throughout this release.
  In addition to the security advisories found by LLMs there have also
  been a large number of other issues identified as well. Many minor fixes are
  present in this release for various situations for issues found in this
  manner.