# rust-lang/miri

An interpreter for Rust's mid-level intermediate representation

Repository: https://github.com/rust-lang/miri
Canonical: https://ross.abutalabs.com/products/miri
Language: Rust
License: Apache-2.0
License Family: permissive
Last push: 2026-08-26T06:48:37+00:00

## Health v2 (maintenance only)
Score: 77/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 35, longevity 100
- inputs: {"age_days": 3947, "days_push": 7, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 6535, forks 518 (observed 2026-08-28T04:09:44.996474+00:00)

## What it is
Miri is an interpreter for Rust's mid-level intermediate representation (MIR) that detects undefined behavior in Rust programs. It runs binaries and cargo test suites to catch unsafe code violations such as use-after-free, out-of-bounds accesses, data races, and aliasing rule violations.

## Use cases
- detect undefined behavior in unsafe rust code
- find use-after-free and out-of-bounds memory bugs
- check for data races in rust programs
- verify memory alignment and type invariants
- detect memory leaks in rust test suites
- test code on big-endian and little-endian targets
- validate stacked borrows aliasing rules

## When to choose
- you write or maintain unsafe Rust code and want to catch UB
- you want to run your cargo test suite under an interpreter to detect memory errors
- you need deterministic execution for debugging
- you want to cross-check byte-level code on different endianness targets

## When to avoid
- you need a security sandbox - Miri's isolation is not a proper sandbox
- you need to generate cryptographic keys - fake RNG makes it unsuitable
- you expect full Rust specification compliance - Miri uses its own UB approximation
- you need to run programs with heavy host system interaction or FFI

## Facets
- artifact type: cli-tool
- maturity: active
- function: interpreter, testing, security
- domain: programming-languages, developer-tools, testing
- platform: rust, cli, windows
- tags: undefined-behavior-detection, unsafe-rust, memory-safety, mir-interpretation, cargo-integration, linux, macos

## Member repositories
- rust-lang/miri (main) score 77

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:44.996474+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:44:07.570355+00:00, confidence not recorded.
  - readme: https://github.com/rust-lang/miri (fetched 2026-08-28T04:09:44.996474+00:00, sha 69a97d403119)
- Data as of 2026-08-30T08:39:29.467469+00:00.