Reported

September 3, 2023

Issued

September 3, 2023 (last modified: September 16, 2024)

Package

lexical (crates.io)

Type

INFO Unsound

Aliases

• GHSA-c2hm-mjxv-89r4

References

• https://github.com/Alexhuszagh/rust-lexical/issues/102
• https://github.com/Alexhuszagh/rust-lexical/issues/101
• https://github.com/Alexhuszagh/rust-lexical/issues/95
• https://github.com/Alexhuszagh/rust-lexical/issues/104
• https://github.com/Alexhuszagh/rust-lexical/issues/126

Patched

• >=7.0.0

Description

lexical contains multiple soundness issues:

1. Bytes::read() allows creating instances of types with invalid bit patterns
2. BytesIter::read() advances iterators out of bounds
3. The BytesIter trait has safety invariants but is public and not marked unsafe
4. write_float() calls MaybeUninit::assume_init() on uninitialized data, which is is not allowed by the Rust abstract machine
5. radix() calls MaybeUninit::assume_init() on uninitialized data, which is is not allowed by the Rust abstract machine

The crate also has some correctness issues.

Alternatives

For quickly parsing floating-point numbers third-party crates are no longer needed. A fast float parsing algorithm by the author of lexical has been merged into libcore.

For quickly parsing integers, consider atoi and btoi crates (100% safe code). atoi_radix10 provides even faster parsing, but only with -C target-cpu=native, and at the cost of some unsafe.

For formatting integers in a #[no_std] context consider the numtoa crate.

For working with big numbers consider num-bigint and num-traits.

Advisory available under CC0-1.0 license.