CVE-2026-97562 smb: client: pin DFS superblock in iterator callback
A race condition in the Linux kernel SMB client allows a use-after-free, potentially leading to system crashes or arbitrary code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-97562?
CVE-2026-97562 is a high-severity use after free vulnerability in Linux, published on 25 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: pin DFS superblock in iterator callback
tcon_super_cb() stores a raw superblock pointer, but __cifs_get_super() takes its active reference only after iterate_supers_type() has dropped s_umount and its passive reference. Concurrent DFS automount expiry can therefore free the superblock before cifs_sb_active() uses it.
A deterministic KASAN test reproduces the race as:
BUG: KASAN: slab-use-after-free in cifs_sb_active+0x77/0x80
The same test passes with this change applied.
Take the active reference in the callback while iterate_supers_type() still holds s_umount shared. cifs_put_tcp_super() remains the matching release.
Which versions are affected by CVE-2026-97562?
How do I fix CVE-2026-97562?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-97562 being exploited?
There is no known exploitation of CVE-2026-97562 in the wild and no public exploit code.
Sources
Also known as AZL-104508, BELL-CVE-2026-97562, DEBIAN-CVE-2026-97562, GHSA-38c4-cggv-4792, UBUNTU-CVE-2026-97562.