Unsound CriticalRUSTSEC-2019-0035 · rand_core
RUSTSEC-2019-0035: Unaligned memory access
Short answerrand_core has an API that can cause undefined behaviour from safe code: Unaligned memory access. Fixed in 0.3.1, 0.4.2.
| Crate | rand_core |
|---|---|
| Type | Unsound |
| Affected versions | Before 0.3.1; from 0.4.0 before 0.4.2. |
| Fixed in | 0.3.1, 0.4.2 |
| Severity | Critical, CVSS 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Published | 2019-04-19 |
| Last changed | 2023-11-08 |
| Also known as | CVE-2020-25576, GHSA-mmc9-pwm7-qj5w |
| Affected functions | rand_core::BlockRng::fill_bytes, rand_core::BlockRng::next_u64 |
What to do
- See which version you have:
cargo tree -i rand_core(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p rand_core. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for examplerand_core = "0.4.2") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
Affected versions of this crate violated alignment when casting byte slices to integer slices, resulting in undefined behavior.
The flaw was corrected by Ralf Jung and Diggory Hardy.
References
- Package: crates.io/crates/rand_core
- Advisory: rustsec.org/advisories/RUSTSEC-2019-0035.html
- Web: github.com/rust-random/rand/blob/master/rand_core/CHANGELOG.md#050---2019-06-06
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
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