Why Rust Is the Right Language for Safety-Critical Medical Software

The choice of programming language for medical software isn't an academic question. It has direct implications for reliability, security, and — in a clinical context — patient safety. Most hospital IT administrators and lab managers don't think about programming language choices when evaluating software, but they probably should.

This post explains why Rust is technically superior to the dominant alternatives for safety-critical software like lab middleware, what the specific guarantees it provides, and why those guarantees matter in a clinical environment.

The Problem With C and C++ in Medical Contexts

Most medical software — including a significant portion of the code running on laboratory instruments — was written in C or C++. These are powerful, fast, and capable languages. They're also the source of the majority of security vulnerabilities discovered in software over the past four decades.

The core issue is memory management. In C and C++, developers manually control memory allocation and deallocation. When this is done incorrectly — which happens at a statistically predictable rate even in well-managed codebases — the result is a class of bugs called memory safety vulnerabilities:

• Buffer overflows: Writing data past the end of an allocated buffer, corrupting adjacent memory
• Use-after-free: Accessing memory after it has been freed and potentially reallocated for other purposes
• Null pointer dereferences: Attempting to access data through a null pointer, causing a crash
• Double-free: Freeing the same memory allocation twice, corrupting the heap
• Race conditions: Two threads accessing and modifying shared data without proper synchronization

Research consistently shows that 60–70% of serious vulnerabilities in large C and C++ codebases are memory safety issues. The Microsoft Security Response Center reported in 2019 that approximately 70% of the CVEs (Common Vulnerabilities and Exposures) they assigned were memory safety related. Google found similar numbers in their Chromium codebase.

In a banking application, a memory safety vulnerability might expose financial data. In medical software, it can cause incorrect results, software crashes during critical patient care moments, or exploitable security weaknesses in systems that handle protected health information.

How Rust Eliminates These Vulnerabilities

Rust takes a fundamentally different approach to memory management. Rather than relying on developers to manually track memory allocation and deallocation, or on a garbage collector that adds unpredictable latency (problematic in real-time systems), Rust uses a compile-time ownership and borrowing system that enforces memory safety at the language level.

Ownership

In Rust, every value has a single "owner" — the variable responsible for it. When the owner goes out of scope, the value is automatically freed. This eliminates use-after-free and double-free vulnerabilities structurally: it's not possible to free memory that's still owned, or to free memory twice, because the ownership system won't allow it.

Borrowing

Rust allows values to be borrowed — temporarily accessed by other code — under strict rules. At any given point, either multiple read-only borrows or exactly one mutable borrow can exist. This enforces at compile time the memory discipline that developers are expected to maintain manually in C++.

No Undefined Behavior

C and C++ have a concept called "undefined behavior" — operations that the language specification says can have any result, including silently corrupting memory. Rust eliminates most undefined behavior by making dangerous operations impossible to express in safe Rust code. The small subset of operations that can't be statically verified (typically direct hardware interaction or FFI calls to other languages) must be explicitly marked as unsafe, making the risky code visible and auditable.

Fearless Concurrency

Rust's ownership system also prevents data race conditions at compile time. Two threads can't simultaneously mutate shared data unless that data is explicitly wrapped in synchronization primitives (like a Mutex). Attempting to do so causes a compile error, not a runtime race condition that only appears under specific timing conditions in production.

Collectively, these features eliminate at compile time the categories of bugs that cause 60–70% of security vulnerabilities in C and C++ systems. The bugs still require developer skill to avoid in other areas — logic errors, incorrect algorithms, integration mistakes — but the entire class of memory safety problems is structurally prevented.

Why This Matters Specifically for Lab Middleware

Lab middleware has characteristics that make memory safety especially important:

Continuous Operation

Middleware runs continuously, often for months between restarts. Memory leaks — gradual loss of memory that would be freed correctly in a safer language — accumulate over time in C++ programs and eventually cause crashes or degraded performance. Rust's ownership model prevents memory leaks in safe code, making long-running stability achievable without scheduled restarts or memory watchdogs.

Concurrent Instrument Connections

A lab with 6 analyzers has 6 concurrent instrument connections being handled simultaneously. Race conditions in the data handling code — a concurrency bug that C++ cannot prevent structurally — can cause result corruption or connection drops. Rust's compile-time data race prevention makes concurrent instrument handling safer to implement correctly.

Real-Time Protocol Parsing

ASTM E1394 and HL7 messages need to be parsed correctly for every result — a buffer overflow in the parser could corrupt adjacent results or cause the middleware to crash. In Rust, bounds checking is automatic (with very low performance overhead compared to C++), making the parser fundamentally safer to implement.

PHI in Memory

Protected health information passes through middleware on its way from instrument to HIS. Use-after-free and buffer overflow vulnerabilities in software that handles PHI create pathways for data exposure or corruption. Rust's memory safety guarantees reduce this risk at the implementation level.

Performance: The Objection That Doesn't Apply

The traditional argument against safe languages in performance-critical systems is that safety comes with a runtime cost. This is true for garbage-collected languages like Java or C# — the garbage collector introduces latency and can cause pauses at unpredictable times.

Rust is different. Its safety guarantees are enforced at compile time, not at runtime. There's no garbage collector, no reference counting overhead in the standard case, and no runtime safety checks beyond the bounds checking that responsible C++ code would perform anyway. Rust programs benchmark comparably to C and C++ on most tasks, with identical control over memory layout and allocation strategy.

For lab middleware — which needs to handle instrument connections reliably and parse results in real-time — Rust offers the performance profile of C++ with the safety guarantees that C++ can't provide.

Rust in the Broader Healthcare Software Ecosystem

Rust is gaining adoption in contexts where safety and correctness are paramount. The Linux kernel — after 30 years of C-only development — began accepting Rust contributions in 2022, driven specifically by memory safety concerns. The U.S. National Security Agency has published guidance recommending memory-safe languages for new software development, explicitly listing Rust as a recommended option. The White House Office of the National Cyber Director published similar guidance in 2024.

In healthcare specifically, the argument is even stronger. FDA-regulated medical device software (SaMD — Software as a Medical Device) is held to rigorous safety standards that memory-safe languages are better positioned to satisfy. While most clinical lab middleware doesn't fall under SaMD regulation, the same engineering principles that make safety-critical devices more reliable apply to software handling patient data.

What LISBridge's Rust Foundation Means in Practice

LISBridge is built with Rust and Tauri — a framework that uses Rust for the application core and React for the UI layer. This means the code responsible for instrument connections, protocol parsing, data processing, and storage is written in a language that prevents the most common categories of software vulnerabilities at compile time.

Practically, this delivers:

• Long-running stability without memory degradation — no "restart the middleware" maintenance window needed
• Safe concurrent handling of multiple instrument connections without race condition risk
• Parser correctness — bounds-checked, overflow-safe parsing of every ASTM and HL7 message
• Predictable performance without garbage collection pauses
• A smaller attack surface for security vulnerabilities in PHI-handling code

For hospital IT administrators and clinical informatics professionals evaluating middleware, this is worth understanding — not as a feature, but as a foundation. The reliability characteristics of lab middleware depend partly on the engineering quality of the code, and the language used is a meaningful signal about that quality.

See how the LISBridge architecture handles instrument connectivity and data processing at lisbridge.com/how-it-works, and how the data parsing layer works at lisbridge.com/solutions/data-parsing.

FAQ

Is Rust widely used in commercial software, or is it still experimental?

Rust is production-proven and widely adopted. It's used in the Linux kernel, Android OS (for new components), Microsoft Windows (for new security-critical components), Mozilla Firefox, Cloudflare's infrastructure, Amazon Web Services, and dozens of other large-scale production systems. It's no longer an emerging language — it's a mature option for systems programming with a growing ecosystem.

Does using Rust make software automatically secure?

No. Rust eliminates memory safety vulnerabilities but doesn't prevent logic errors, incorrect algorithm implementations, integration mistakes, or poor security practices at the application level. A Rust program can still have serious bugs — they just won't be the class of bugs (buffer overflows, use-after-free, race conditions) that Rust is specifically designed to prevent. Good engineering practices, code review, and testing still matter.

What's the difference between Rust safety and FDA safety certification?

Rust's memory safety guarantees are language-level properties that prevent specific categories of bugs at compile time. FDA safety certification (for SaMD and medical devices) is a regulatory framework that evaluates a product's overall safety and effectiveness, including clinical validation, risk management, and quality systems. They address different aspects of safety and are independent of each other. Rust helps write more correct code; FDA certification evaluates whether a product is safe and effective for its intended clinical use.

Why don't more medical software vendors use Rust?

Rust has a steeper learning curve than C++ for experienced C++ developers, and most medical software was written before Rust reached maturity (1.0 was released in 2015). Existing codebases in C++ are expensive to rewrite. New products and greenfield development have a much stronger case for using Rust from the start — which is exactly the position LISBridge was designed from.

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