CVE-2026-90162 ksmbd: defer publishing granted locks to prevent UAF/double-free race
A race condition in the Linux kernel's ksmbd module allows attackers to trigger a use-after-free and double-free, potentially leading to code execution or privilege escalation.
- 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-2026-90162?
CVE-2026-90162 is a high-severity use after free vulnerability in Linux, published on 17 Sep 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: defer publishing granted locks to prevent UAF/double-free race
In smb2_lock(), mid-batch granted locks are published to connection-wide (conn->lock_list) and file-wide (fp->lock_list) lists immediately upon vfs_lock_file() success, while also remaining tracked on the stack-local rollback_list.
If a subsequent element in the same SMB2_LOCK request array fails validation or execution, the thread jumps to out: and walks rollback_list to undo previously granted locks. However, because the granted lock was already published to conn->lock_list, a concurrent UNLOCK request on the same connection can find the lock object and kfree() it before the rollback loop executes.
When the granting thread subsequently walks rollback_list, it dereferences and frees the already-freed ksmbd_lock structure, resulting in a Use-After-Free and Double-Free (on both ksmbd_lock and struct file_lock).
Fix this by deferring the publication of granted locks to conn->lock_list and fp->lock_list until after the entire array of lock elements has been processed without error. Mid-batch grants remain tracked exclusively on the request-local rollback_list until the whole batch succeeds, eliminating the race window.
Which versions are affected by CVE-2026-90162?
How do I fix CVE-2026-90162?
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-2026-90162 being exploited?
There is no known exploitation of CVE-2026-90162 in the wild and no public exploit code.
Sources
Also known as AZL-102770, BELL-CVE-2026-90162, DEBIAN-CVE-2026-90162, GHSA-x2qc-qfqc-6vmr, UBUNTU-CVE-2026-90162.