How to Update Rust to 1.94.1 and Apply Critical Fixes

Introduction

The Rust team has released a new point version, Rust 1.94.1, which addresses several regressions introduced in the previous version and includes important security patches. If you're already using Rust via rustup, upgrading is straightforward. This step-by-step guide will walk you through the update process, explain what changes are included, and provide tips to ensure everything works smoothly.

Whether you're a seasoned Rustacean or new to the ecosystem, keeping your toolchain up-to-date is essential for performance, stability, and safety. Let's get started.

What You Need

• A working installation of Rust obtained via rustup (if you don't have it, get it from rustup.rs).
• An internet connection to download the new version.
• Basic familiarity with command-line operations (terminal/command prompt).
• Optional: A test project to verify the fixes.

Step-by-Step Guide

Step 1: Check Your Current Rust Version

Before updating, it's a good practice to note your current version. Open your terminal and run:

rustc --version

If your output shows rustc 1.94.0 (or earlier), you're eligible for this update. If you're already on 1.94.1, you can skip to the end to review the fixes.

Step 2: Update Your Rust Installation

With rustup, updating to the latest stable release is a one-command process. Execute:

rustup update stable

This command will download and install Rust 1.94.1 along with its associated components (Cargo, clippy, etc.). You'll see progress messages as the toolchain updates.

Step 3: Confirm the Update

After the update completes, verify that you're now running the new version:

rustc --version

The output should display rustc 1.94.1. You can also check Cargo's version with cargo --version.

What's Fixed in 1.94.1

Understanding the changes helps you take advantage of the fixes. The release resolves three regressions from 1.94.0 and includes two security patches.

Fix for std::thread::spawn on wasm32-wasip1-threads

If you develop WebAssembly applications using the wasip1 threads target, a regression in 1.94.0 prevented std::thread::spawn from working correctly. This is now resolved. You can test by compiling a simple threaded program for that target.

Removal of New Methods on std::os::windows::fs::OpenOptionsExt

The previous release added new unstable methods to this trait. Because the trait is not sealed, adding non-default methods could break external implementations. Therefore, those methods were removed. If you were using them, you'll need to adjust your code (they were unstable, so likely not widespread). No action is needed unless your code relied on these additions.

Clippy: Fix ICE in match_same_arms

An internal compiler error (ICE) that occurred when running clippy's match_same_arms lint has been fixed. Run cargo clippy on your projects; previously problematic patterns should now analyze correctly.

Cargo: Downgrade curl-sys to 0.4.83

Some users on specific FreeBSD versions encountered certificate validation errors due to an upstream issue in curl-sys. The Cargo team reverted to a stable version that avoids this problem. If you use Cargo on FreeBSD, your network operations should now proceed without errors.

Security Fixes: Cargo Updates tar to 0.4.45

Two CVEs (CVE-2026-33055 and CVE-2026-33056) were addressed by updating the tar crate. Users of crates.io are not affected by these specific vulnerabilities. However, to stay secure, ensure your project's lockfile is updated by running cargo update after upgrading Rust.

Verifying the Fixes

After updating, you can confirm the fixes apply to your environment:

1. For the wasm spawn fix: Compile a test program targeting wasm32-wasip1-threads. If it previously failed, it should now succeed.
2. For Clippy: Run cargo clippy on a codebase that triggered the ICE. Check that no internal errors appear.
3. For the curl-sys downgrade: If you're on FreeBSD, test a cargo publish or any network operation that uses HTTPS.
4. For security: Update your dependencies with cargo update and ensure the tar crate version in Cargo.lock is at least 0.4.45.

Tips for a Smooth Experience

• Keep rustup itself updated: Run rustup self update periodically to ensure you have the latest installer features.
• Use nightly for experimental features: If you need features not yet stable, you can switch with rustup toolchain install nightly. But remember to return to stable for production work.
• Check the official blog: For detailed information about regressions and security patches, refer to the Rust blog announcement.
• Test your projects: After upgrading, run your test suite to catch any compatibility issues early.
• Contribute to Rust: Hundreds of contributors help make Rust better. If you find a bug, consider reporting it on the issue tracker.

By following these steps, you've successfully updated to Rust 1.94.1 and applied critical fixes. Happy coding!