CVE-2026-74522 ksmbd: fix use-after-free in __close_file_table_ids()
A use-after-free in the Linux kernel's ksmbd module allows attackers to execute arbitrary code or escalate privileges via crafted file operations.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74522?
CVE-2026-74522 is a high-severity use after free vulnerability in Linux, published on 15 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix use-after-free in __close_file_table_ids()
A ksmbd_file can remain alive after logical close while another session holds a temporary reference obtained through ksmbd_lookup_fd_inode(). ksmbd_close_fd() currently marks the file closed and drops the idr-owned reference, but leaves the pointer published in the closing session's idr until the final reference is dropped.
If the foreign holder performs the final ksmbd_fd_put(), __put_fd_final() supplies the foreign session's file table to __ksmbd_close_fd(). The object is then freed without being removed from its owner's idr, and the owner session later dereferences the stale pointer during file-table teardown.
Remove the volatile id from the owner's idr while ksmbd_close_fd() still holds that table's lock, and clear volatile_id before dropping the idr-owned reference. A later foreign final put then only performs physical destruction and cannot remove the object from the wrong table.
Which versions are affected by CVE-2026-74522?
How do I fix CVE-2026-74522?
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-2026-74522 being exploited?
There is no known exploitation of CVE-2026-74522 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74522, DEBIAN-CVE-2026-74522, GHSA-r5jm-2247-f5r8, UBUNTU-CVE-2026-74522.