RUSTSEC-2022-0031: Panic due to improper UTF-8 indexing

What to do

1. See which version you have: cargo tree -i rulex (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p rulex. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example rulex = "0.4.3") 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

When parsing untrusted rulex expressions, rulex may panic, possibly enabling a Denial of Service attack. This happens when the expression contains a multi- byte UTF-8 code point in a string literal or after a backslash, because rulex tries to slice into the code point and panics as a result.

The flaw was corrected in commits fac6d58b25 and 330b3534e7 by using len_utf8() to derive character width in bytes instead of assuming ASCII encoding of 1 byte per char.

References

• Package: crates.io/crates/rulex
• Advisory: rustsec.org/advisories/RUSTSEC-2022-0031.html
• Web: github.com/rulex-rs/rulex/commit/fac6d58b25c6f9f8c0a6cdc4dec75b37b219f1d6

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

Other advisories for rulex

• VulnerabilityRUSTSEC-2022-0030 · 2022-05-21Stack overflow during recursive expression parsing

Full security history of rulex