6 Critical Fixes in Rust 1.94.1 That Every Developer Needs to Understand

The Rust team has shipped version 1.94.1, a point release that addresses several regressions introduced in the previous stable update. This release also includes a security patch for Cargo's tar dependency. If you're using an older stable release through rustup, upgrading is straightforward. Below, we break down the six most important changes you need to know about—from WebAssembly fixes to certificate validation improvements. As always, a big thank you to the contributors who made this release possible.

1. How to Update to Rust 1.94.1

Getting the latest stable Rust is as simple as running rustup update stable in your terminal. If you haven't installed Rust yet, you can grab rustup from the official website. The update pulls down the new compiler and tools, ensuring you have all the fixes described below. No additional steps are required—just a single command and you're ready to go. If you're still on Rust 1.93 or earlier, this update will bring you straight to 1.94.1, skipping the problematic 1.94.0 entirely.

2. WebAssembly Threads: std::thread::spawn Works Again on wasm32-wasip1-threads

Rust 1.94.0 introduced a regression that broke the std::thread::spawn function for the wasm32-wasip1-threads target. This is a critical issue for developers targeting WebAssembly with threading support, as the function is the primary way to create new threads. In 1.94.1, the underlying bug has been resolved, and std::thread::spawn now behaves correctly again. If you were experiencing runtime failures or crashes when using threads in your WASM projects, this update will restore normal functionality. Always test your threaded code after upgrading to ensure everything works as expected.

3. Windows API Cleanup: Removed Unstable Methods from OpenOptionsExt

In Rust 1.94.0, new methods were added to the std::os::windows::fs::OpenOptionsExt trait. While these methods were marked unstable, the trait itself is not sealed, meaning it can be implemented by external crates. Adding new methods to a non-sealed trait can cause breaking changes for implementors. To prevent this, the Rust team decided to remove the newly added methods from the trait entirely. This fix ensures stability for any crate that implements OpenOptionsExt. If you were using these methods (which were only available on nightly), you'll need to adapt your code—but most developers on stable Rust won't be affected.

4. Clippy: No More Internal Compiler Errors in match_same_arms

The popular linting tool Clippy encountered an internal compiler error (ICE) when analyzing certain match expressions with identical arms. This regression, introduced in 1.94.0, caused Clippy to crash instead of producing a helpful warning. The 1.94.1 release patches this ICE, so clippy::match_same_arms now runs smoothly. If you rely on Clippy as part of your continuous integration pipeline, this fix will prevent spurious failures and allow your linting process to complete successfully. As always, keep your tooling up to date to avoid such hiccups.

5. Cargo: Downgraded curl-sys to Fix Certificate Validation on FreeBSD

Some users on specific versions of FreeBSD encountered certificate validation errors when using Cargo. The root cause was traced back to the curl-sys crate, which Cargo uses for network operations. In response, the Rust team downgraded curl-sys from 0.4.84 to 0.4.83, reverting the change that introduced the validation failure. If you're on FreeBSD and previously saw errors like certificate verify failed, upgrading to Rust 1.94.1 will resolve them. For more details, check the related issue (hypothetical link). This fix ensures that Cargo can securely download dependencies without manual intervention.

6. Security Patch: Updated tar Crate to Address CVEs

Two security vulnerabilities—CVE-2026-33055 and CVE-2026-33056—were discovered in the tar crate, which Cargo uses to unpack compressed archives. Rust 1.94.1 updates tar to version 0.4.45, which contains fixes for these issues. While the vulnerabilities do not affect users of crates.io directly (since the crate is only used during local development), it's still important to upgrade to eliminate any risk. If you're building or managing custom packages that rely on tar, this update provides a safer environment. The Rust team recommends all users apply this patch as part of their regular maintenance cycle.

With these six fixes, Rust 1.94.1 delivers a more stable and secure experience for everyone. The contributors behind this release deserve recognition—their hard work keeps the language reliable and robust. If you haven't updated yet, run rustup update stable now. Stay tuned for future releases and continue building amazing software with Rust.