A Time-of-Check to Time-of-Use (TOCTOU) vulnerability exists in the install utility of uutils coreutils when using the -D flag. The command creates parent directories and subsequently performs a second path resolution to create the target file, neither of which is anchored to a directory file descriptor. An attacker with concurrent write access can replace a path component with a symbolic link between these operations, redirecting the privileged write to an arbitrary file system location.

Affected: crates.io: uu_install

The `-D` path runs `fs::create_dir_all` on a pathname then later opens the destination via path-based `File::create`/`fs::copy`, neither anchored to a directory fd. Between the two, an attacker can replace a path component with a symlink, redirecting the write.

**Impact:** an attacker with concurrent write access to the destination tree can redirect a privileged `install -D` to an arbitrary location, enabling arbitrary file overwrite with attacker-controlled content. Recommendation: use dirfd-based traversal (`openat`/`mkdirat` + `O_NOFOLLOW`) per component and create the destination via `openat` on the same dirfd.

**Remediation:** Acknowledged by Canonical; fixed in commit 0c412999.

--- _Reported by Zellic in the *uutils coreutils Program Security Assessment* (prepared for Canonical, Jan 20 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`. Finding 3.51. Credit: Zellic._

Affected: Ubuntu:24.04:LTS: rust-coreutils, Ubuntu:25.10: rust-coreutils

A Time-of-Check to Time-of-Use (TOCTOU) vulnerability exists in the install utility of uutils coreutils when using the -D flag. The command creates parent directories and subsequently performs a second path resolution to create the target file, neither of which is anchored to a directory file descriptor. An attacker with concurrent write access can replace a path component with a symbolic link between these operations, redirecting the privileged write to an arbitrary file system location.