CVE-2026-35355

`copy_file` in `install/src/install.rs` removes the destination then recreates it by pathname via `File::create` / `fs::copy` without `O_EXCL`/`create_new`. Between the unlink and the recreate, a local attacker with write access to the destination directory can drop in a symlink and redirect the write. **Impact:** when `install` runs privileged into an attacker-writable directory (staging/build paths), the race allows redirecting writes to arbitrary files and overwriting sensitive system files (`/etc/passwd`, `/etc/shadow`). Recommendation: create atomically with `create_new`/`O_EXCL` and copy via the opened fd rather than reopening by path. **Remediation:** Acknowledged by Canonical; fixed in commit b5bbabc1. --- _Reported by Zellic in the *uutils coreutils Program Security Assessment* (prepared for Canonical, Jan 20 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`. Finding 3.50. Credit: Zellic._

### Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-239g-2685-54x3. This link is maintained to preserve external references. ### Original Description The install utility in uutils coreutils is vulnerable to a Time-of-Check to Time-of-Use (TOCTOU) race condition during file installation. The implementation unlinks an existing destination file and then recreates it using a path-based operation without the O_EXCL flag. A local attacker can exploit the window between the unlink and the subsequent creation to swap the path with a symbolic link, allowing them to redirect privileged writes to overwrite arbitrary system files.