Cargo is a package manager for the rust programming language. After a package is downloaded, Cargo extracts its source code in the ~/.cargo folder on disk, making it available to the Rust projects it builds. To record when an extraction is successful, Cargo writes "ok" to the .cargo-ok file at the root of the extracted source code once it extracted all the files. It was discovered that Cargo allowed packages to contain a .cargo-ok symbolic link, which Cargo would extract. Then, when Cargo attempted to write "ok" into .cargo-ok, it would actually replace the first two bytes of the file the symlink pointed to with ok. This would allow an attacker to corrupt one file on the machine using Cargo to extract the package. Note that by design Cargo allows code execution at build time, due to build…