RUSTSEC-2021-0012: Reading uninitialized memory can cause UB (`Deserializer::read_vec`)

What to do

1. See which version you have: cargo tree -i cdr (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p cdr. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example cdr = "0.2.4") 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

Deserializer::read_vec() created an uninitialized buffer and passes it to a user-provided Read implementation (Deserializer.reader.read_exact()).

Passing an uninitialized buffer to an arbitrary Read implementation is currently defined as undefined behavior in Rust. Official documentation for the Read trait explains the following: "It is your responsibility to make sure that buf is initialized before calling read. Calling read with an uninitialized buf (of the kind one obtains via MaybeUninit<T>) is not safe, and can lead to undefined behavior."

The flaw was corrected in commit ce310f7 by zero-initializing the newly allocated buffer before handing it to Deserializer.reader.read_exact().

References

• Package: crates.io/crates/cdr
• Advisory: rustsec.org/advisories/RUSTSEC-2021-0012.html
• Report: github.com/hrektts/cdr-rs/issues/10

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