GHSA-4c7q-4928-8445

chmod: --preserve-root bypassed by any path that resolves to root (e.g. /../)

`Chmoder::chmod()` only compares the literal argument against `Path::new("/")`, so the `--preserve-root` guard is bypassed by any path that *resolves* to root — a symlink to `/` or simply `/../`. ``` if self.recursive && self.preserve_root && file == Path::new("/") { return Err(ChmodError::PreserveRoot("/".to_string()).into()); } ``` **PoC** — recursively chmods the entire filesystem to `000` despite `--preserve-root`: ``` chmod -R --preserve-root 000 /../ -v ``` **Impact:** `--preserve-root` is the documented safeguard against destructive recursive operations on `/`. Bypassing it allows `chmod -R` to alter permissions across the whole filesystem, causing a complete system breakdown. Recommendation: canonicalize the target path before comparing against root. **Remediation:** Acknowledged by Canonical; fixed in commit 413055b3. --- _Reported by Zellic in the *uutils coreutils Program Security Assessment* (prepared for Canonical, Jan 20 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`. Finding 3.1. Credit: Zellic._