Wasmtime is a lightweight WebAssembly runtime built for speed, security, and standards-compliance. Wasmtime now supports long-term-support (LTS) releases that are maintained with security fixes for 2 years after their initial release.

The Wasmtime project releases a new version once a month with new features, bug fixes, and performance improvements. Previously though these releases were only supported for 2 months meaning that embedders needed to follow the Wasmtime project pretty closely to receive security updates. This rate of change can be too fast for users so Wasmtime now supports LTS releases.

Every 12th version of Wasmtime will now be considered an LTS release and will receive security fixes for 2 years, or 24 months. This means that users can now update Wasmtime once-a-year instead of once-a-month and be guaranteed that they will always receive security updates. Wasmtime’s 24.0.0 release has been retroactively classified as a LTS release and will be supported until August 20,

  1. Wasmtime’s upcoming 36.0.0 release on August 20, 2025 will be supported until August 20, 2027, meaning that users will have one year starting in August to upgrade from 24.0.0 to 36.0.0.

You can view a table of Wasmtime’s releases in the documentation book which has information on all currently supported releases, upcoming releases, and information about previously supported releases. The high-level summary of Wasmtime’s LTS release channel is:

  • LTS releases receive patch updates for 2 years after their initial release.
  • Patch releases are guaranteed to preserve API compatibility.
  • Patch releases strive to maintain tooling compatibility (e.g. the Rust version required to compile Wasmtime) from the time of release. Depending on EOL dates from components such as GitHub Actions images, however, this may need minor updates.
  • Patch releases are guaranteed to be issued for any security bug found in historical releases of Wasmtime.
  • Patch releases may be issued to fix non-security released bugs as they are discovered. The Wasmtime project will rely on contributions to provide backports for these fixes.
  • Patch releases will not be issued for new features to Wasmtime, even if a contribution is made to backport a new feature.

If you’re a current user of Wasmtime and would like to use an LTS release then it’s recommended to either downgrade to the 24.0.0 version or wait for this August to upgrade to the 36.0.0 version. Wasmtime 34.0.0, to be released June 20, 2025, will be supported up until the release of Wasmtime 36.0.0 on August 20, 2025.