CVE-2026-68381 ksmbd: pin conn during async oplock break notification
A race condition in the Linux kernel ksmbd module allows use-after-free during oplock break notifications, potentially leading to code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68381?
CVE-2026-68381 is a critical use after free vulnerability in Linux, published on 10 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: pin conn during async oplock break notification
smb2_oplock_break_noti() and smb2_lease_break_noti() store a ksmbd_conn pointer in an async ksmbd_work and then queue that work on ksmbd-io. The work only increments conn->r_count, which prevents teardown from passing the pending-request wait after the increment, but it does not pin the struct ksmbd_conn object.
If connection teardown races with an oplock break notification, the last conn reference can be dropped before the queued worker finishes. The worker then uses the freed conn in ksmbd_conn_write() and ksmbd_conn_r_count_dec().
Take a real conn reference when publishing the conn pointer to the async work item, and drop it after the notification work has decremented r_count. Apply the same lifetime rule to lease break notification, which uses the same work->conn pattern.
Weakness: CWE-416
Which versions are affected by CVE-2026-68381?
How do I fix CVE-2026-68381?
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-2026-68381 being exploited?
There is no known exploitation of CVE-2026-68381 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68381, DEBIAN-CVE-2026-68381, GHSA-gq9g-pv9h-2q5v, UBUNTU-CVE-2026-68381.