Rust advisories / appendix
Vulnerability MediumRUSTSEC-2020-0149 · appendix
RUSTSEC-2020-0149: Data race and memory safety issue in `Index`
Short answerA security vulnerability in the appendix crate: Data race and memory safety issue in `Index`. Medium severity (CVSS 5.9). No fixed version: replace the crate or remove the affected code path.
| Crate | appendix |
|---|---|
| Type | Vulnerability (memory-corruption, thread-safety) |
| Affected versions | Every version. |
| Fixed in | none |
| Severity | Medium, CVSS 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |
| Published | 2020-11-15 |
| Last changed | 2023-11-08 |
| Also known as | CVE-2020-36469, GHSA-fvhr-7j8m-3cvc |
What to do
- Find who pulls it in:
cargo tree -i appendix. - Avoid the affected API, or replace the crate.
Details from the advisory
The appendix crate implements a key-value mapping data structure called Index<K, V> that is stored on disk. The crate allows for any type to inhabit the generic K and V type parameters and implements Send and Sync for them unconditionally.
Using a type that is not marked as Send or Sync with Index can allow it to be used across multiple threads leading to data races. Additionally using reference types for the keys or values will lead to the segmentation faults in the crate's code.
References
- Package: crates.io/crates/appendix
- Advisory: rustsec.org/advisories/RUSTSEC-2020-0149.html
- Report: github.com/krl/appendix/issues/6
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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