Rust in Cybersecurity: Where Memory Safety Actually Changes the Game
Rust generates strong opinions, and in security circles the enthusiasm is especially loud. Some of it is hype, but underneath the hype is a real claim worth taking seriously: Rust’s memory-safety guarantees address an entire class of vulnerabilities at the language level, which is a genuine security property, not merely a developer-experience improvement. The question for a security practitioner is where that actually changes the game — and where the enthusiasm overshoots into treating Rust as a security panacea.
This is an attempt at the honest version: where Rust meaningfully matters in cybersecurity, and where it does not.
The core claim: a whole vulnerability class, eliminated by design
The substantive argument: a large fraction of serious security vulnerabilities historically come from memory-safety errors — buffer overflows, use-after-free, and related bugs where code accesses memory it should not. These have been among the most exploited and most damaging vulnerability classes for decades. Rust’s ownership-and-borrowing model prevents this class of error at compile time — code that would commit these mistakes does not compile.
This is genuinely significant. It is not “Rust makes these bugs less likely through good practice” — it is “Rust makes this class of bug structurally impossible in safe code, enforced by the compiler.” For software where memory-safety vulnerabilities are the dominant risk (systems software, network-facing code, anything handling untrusted input in a low-level language), choosing Rust eliminates the largest historical source of vulnerabilities by construction. That is a real security property, paid for in compile-time discipline rather than runtime checks.
This is why the push toward memory-safe languages for security-critical software is not fashion — it is recognition that an entire category of catastrophic vulnerabilities can be designed out rather than tested for.
Where Rust matters in security work
Concretely, where this changes things:
Writing security-critical software. For software where a memory-safety vulnerability would be catastrophic — anything parsing untrusted input, network-facing services, systems components — Rust’s guarantees mean the most dangerous vulnerability class is off the table in safe code. For new security-sensitive software, this is a strong argument, and increasingly the responsible default where performance requirements once forced C or C++.
Building security tooling. For practitioners building their own tools, Rust offers a combination that fits security work well: the safety guarantees, performance comparable to C, and a single compiled binary that deploys cleanly without a runtime. A security tool that handles potentially-hostile input (parsing untrusted data is constant in security tooling) benefits from the language refusing to let that input trigger memory-safety bugs. The safety is most valuable exactly where security tools operate — at the boundary with untrusted data.
Replacing C/C++ in security-sensitive positions. Where existing C/C++ code is a memory-safety liability, rewriting security-critical components in Rust addresses the vulnerability class directly. This is the rationale behind the broad movement to bring Rust into historically-C codebases at their most security-sensitive points.
Where the enthusiasm overshoots
A credible take has to push back on the hype, because Rust-as-panacea is wrong in instructive ways:
Memory safety is not all of security. Rust eliminates memory-safety vulnerabilities; it does nothing for logic flaws, injection vulnerabilities, authentication and authorization errors, cryptographic mistakes, or design-level security problems. A Rust program can be thoroughly insecure through bad logic, bad auth, or bad design — the language guarantees say nothing about these. Treating “written in Rust” as “secure” is a category error: it addresses one (important) class and leaves every other class untouched.
unsafe exists and undoes the guarantees. Rust’s safety applies to safe code; the unsafe keyword lets you opt out for cases that require it, and within unsafe blocks the guarantees do not hold. Security-relevant Rust code that uses unsafe (sometimes necessary) reintroduces exactly the risks Rust otherwise prevents — so the safety is real but not unconditional, and unsafe blocks deserve the scrutiny that all of C would.
Dependencies carry their own risk. A Rust program depends on a tree of libraries, and the safety of your code says nothing about supply-chain risk in your dependencies — a compromised or vulnerable dependency is a problem regardless of the language. Rust’s safety is not a supply-chain control.
The learning curve is real and has a cost. Rust’s model is genuinely harder to learn, and that cost is real — slower development during ramp-up, a smaller pool of fluent developers. For some projects that cost outweighs the safety benefit, and pretending otherwise is dishonest. The right choice depends on whether memory safety is actually the dominant risk for this software.
The balanced position
The honest stance: Rust meaningfully changes the game for the specific (large, important) class of memory-safety vulnerabilities, and changes nothing for the many other classes of security problem. That makes it a strong choice for new security-critical and untrusted-input-handling software, and for security tooling, where the safety guarantee lands exactly where the risk is. It does not make software secure — it removes one major category of insecurity, leaving the rest to design, logic, and discipline.
For a security practitioner building tools, the practical read: Rust is an excellent default for tooling that handles hostile input and needs performance and clean deployment, because the safety guarantee aligns with where security tools operate — but the language doing the memory-safety work does not excuse you from the logic, auth, crypto, and design work that constitutes the rest of security.
The takeaway
Rust’s memory-safety guarantees are a genuine security property: they eliminate, by compile-time construction, the vulnerability class that has caused a disproportionate share of serious security failures for decades. That is real and important — it makes Rust a strong, increasingly-default choice for new security-critical software and for security tooling that handles untrusted input. But it addresses one class, and “written in Rust” is not “secure” — logic, injection, auth, crypto, design, dependencies, and unsafe all remain entirely your problem.
The reframe to carry: Rust designs out the largest historical vulnerability class, which is a real and valuable security property — and it leaves every other class exactly where it was. Reach for it where memory safety is the dominant risk and the safety lands where your code meets hostile input; do not mistake it for security itself.
An independent piece by johlem.net — IT security, Luxembourg. Secure tooling development.