The --preserve-root check uses a path-string test (path.has_root() && path.parent().is_none()) rather than comparing device/inode. A symlink to / (e.g. /tmp/rootlink -> /) has a parent component, so it passes the check. GNU caches /'s dev/inode at startup and compares every traversed directory against it.
Impact: rm -rf --preserve-root on a path that resolves through a symlink to / bypasses protection and can delete system directories. Recommendation: compare each entered directory's dev/inode against cached /.
Remediation: Acknowledged by Canonical; fixed in commit 5e5968cd.
Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.44. Credit: Zellic.
References
The
--preserve-rootcheck uses a path-string test (path.has_root() && path.parent().is_none()) rather than comparing device/inode. A symlink to/(e.g./tmp/rootlink -> /) has a parent component, so it passes the check. GNU caches/'s dev/inode at startup and compares every traversed directory against it.Impact:
rm -rf --preserve-rooton a path that resolves through a symlink to/bypasses protection and can delete system directories. Recommendation: compare each entered directory's dev/inode against cached/.Remediation: Acknowledged by Canonical; fixed in commit 5e5968cd.
Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit
3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.44. Credit: Zellic.References