Rust 1.99.1 was released on October 15, 2026, addressing three serious bugs from the previous version 1.99.0, two of which were classified as critical. The most significant issue involved a silent miscompilation of boolean values across a foreign function interface on x86_64 architecture, leading to incorrect return values. Additionally, a linker failure on macOS prevented the loading of a necessary library, and a missing symbol caused link errors on UEFI targets. The rapid turnaround in fixing these regressions, completed in about two weeks, highlights Rust's commitment to maintaining code stability, with users advised to update their installations using the command `rustup update stable`

Rust 1.99.1 Released: Three Critical Bugs Fixed in Record Two-Week Turnaround

Rust's release team shipped 1.99.1 on October 15, 2026, clearing three serious regressions that had slipped into last month's stable release, 1.99.0. Two of the bugs are critical: a silent FFI bool miscompilation on x86_64 that returned garbage instead of clean booleans, and a macOS linker failure where rust-lld couldn't find libLLVM.dylib when invoking rustc directly. A third, rated high, caused link errors on UEFI targets due to a missing wcslen symbol born from a narrow code backport. All three were diagnosed and fixed in about two weeks, so simply running rustup update stable brings you up to date.

Rust 1.99.1 Released: Three Critical Bugs Fixed in Record Two-Week Turnaround @ Linux Compatible