Microsoft has elevated Rust to "Tier One" status among its canonical programming languages, placing it alongside C++, C#, and TypeScript as the most supported options for internal development, according to a report from The Register published this week. Victor Ciura, a principal engineer on Microsoft's Rust tooling team, announced the promotion during a keynote address at RustConf 2026 in Montréal. The designation means Redmond has built a complete "path" of tools and workflows that enable Rust development throughout the company's entire software creation cycle.
The language already appears in more than 100 Microsoft project repositories, the report notes. Microsoft created Oxidizer, a collection of crates for constructing scalable services in Rust, which engineers have deployed to build and improve Microsoft 365 core services including Outlook, Word, Excel, OneDrive, and SharePoint. The Copilot technology stack also relies heavily on Rust. Company engineers built rustc_codegen_utc, a custom compiler code-generation backend that connects the rustc compiler straight into MSVC's internal toolchain for Windows, creating what Ciura described in a blog post as "a unified code generation platform for Rust and C++ on Windows."
According to Ciura's blog post, linking rustc to that backend allows Rust to build on the same platform investment with perfect compatibility right out of the box, rather than needing a separate implementation of every Windows-specific feature. Microsoft Azure CTO Mark Russinovich noted in his 2025 RustConf keynote that roughly 70 percent of Windows CVEs stem from memory issues. "One of the things that I realized a long time ago is that no matter how much we really want to make C and C++ better, we can't make it as good as what Rust starts with," Russinovich said.
The move addresses a persistent vulnerability challenge for Microsoft, particularly given recent Windows Patch Tuesday update volumes, the report suggests. Mozilla developer Graydon Hoare created Rust in 2006 as a side project, primarily to deliver high-performance code that, unlike C and C++, protected against memory bugs. The report notes that despite tight Rust integration, Microsoft engineers face considerable challenges ahead, especially in the "unsafe" territory that emerges when mixing Rust and C++ code—while the Rust compiler can flag memory errors, it typically doesn't cover pointers into C++ memory allocations. Rewriting programs in Rust to boost performance and reduce bugs has become standard practice for project leaders, who have converted everything from databases to package managers, often with AI assistance. Microsoft's embrace of Rust as a top-tier language positions the company to systematically address the memory safety issues that account for the majority of its Windows security vulnerabilities. The language's integration into Redmond's primary development workflows means engineers can now choose Rust without facing tooling or process barriers that previously limited its use. For enterprise software development, the strategic shift acknowledges that legacy language constraints cannot be incrementally patched away when foundational architecture determines exposure.