RUSTSEC-2023-0014: Miscompilation in cortex-m-rt 0.7.1 and 0.7.2

What to do

1. See which version you have: cargo tree -i cortex-m-rt (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p cortex-m-rt. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example cortex-m-rt = "0.7.3") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

Version 0.7.1 of the cortex-m-rt crate introduced a regression causing the stack to NOT be eight-byte aligned prior to calling main (or any other specified entrypoint), violating the stack ABI of AAPCS32, the default ABI used by all Cortex-M targets. This regression is also present in version 0.7.2 of the cortex-m-rt crate.

This regression can cause certain compiler optimizations (which assume the eight-byte alignment) to produce incorrect behavior at runtime. This incorrect behavior has been observed in real-world applications.

**It is advised that ALL users of v0.7.1 and v0.7.2 of the cortex-m-rt crate update to the latest version (v0.7.3), AS SOON AS POSSIBLE.** Users of v0.7.0 and prior versions of cortex-m-rt are not affected by this regression.

It will be necessary to rebuild all affected firmware binaries, and flash or deploy the new firmware binaries to affected devices.

References

• Package: crates.io/crates/cortex-m-rt
• Advisory: rustsec.org/advisories/RUSTSEC-2023-0014.html
• Web: github.com/rust-embedded/cortex-m/discussions/469

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.