Executive brief
GNOME gvfs is a virtual filesystem implementation used by Linux desktop environments to manage file access and storage. A flaw in the privileged gvfsd-admin daemon allows a local attacker to change ownership of critical system files through a race condition, leading to full root-level compromise. An authenticated attacker can exploit this to modify system configuration files and gain administrative control over the system.
Technical details
The vulnerability is a Time-of-Check Time-of-Use (TOCTOU) race condition in the gvfsd-admin daemon's handling of D-Bus socket ownership. The daemon uses the link-following chown() function on a pathname inside a user-controlled directory without proper synchronization. An attacker can replace the socket pathname with a symbolic link pointing to an arbitrary root-owned file (such as /etc/pam.d/su) between the permission check and the chown operation. The daemon follows the symlink and changes the target file's ownership to the attacker's user ID, enabling modification of critical system files. The attack requires local authentication and a precise timing window but results in privilege escalation to root.
Affected products
- GNOME gvfs
Timeline
- 2026-09-10: disclosed