Rust advisories / libyml
Unsound HighRUSTSEC-2025-0067 · libyml
RUSTSEC-2025-0067: `libyml::string::yaml_string_extend` is unsound and unmaintained
Short answerlibyml has an API that can cause undefined behaviour from safe code: `libyml::string::yaml_string_extend` is unsound and unmaintained. No fixed version yet.
| Crate | libyml |
|---|---|
| Type | Unsound |
| Affected versions | Every version. |
| Fixed in | none |
| Severity | High (GitHub rating) |
| Published | 2025-09-11 |
| Last changed | 2025-10-28 |
| Also known as | GHSA-gfxp-f68g-8x78 |
What to do
- Find who pulls it in:
cargo tree -i libyml. - Avoid the affected API, or replace the crate.
Details from the advisory
In version 0.0.4, libyml::string::yaml_string_extend was revised resulting in undefined behaviour, which is unsound.
The GitHub project for libyml was archived after unsoundness issues were raised.
If you rely on this crate, it is highly recommended switching to a maintained alternative.
Recommended alternatives
libyaml-saferunsafe-libyaml-norway- Maintained fork ofunsafe-libyaml
References
- Package: crates.io/crates/libyml
- Advisory: rustsec.org/advisories/RUSTSEC-2025-0067.html
- Report: github.com/rustsec/advisory-db/issues/2395
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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