CVE-2026-64393 ksmbd: run set info with opener credentials
Attackers can escalate privileges by exploiting credential mishandling in the ksmbd SMB server when setting file information.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64393?
CVE-2026-64393 is a critical vulnerability in Linux kernel, published on 25 Jul 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: run set info with opener credentials
SMB2 SET_INFO handlers call path-based VFS helpers after checking the access mask granted to the SMB handle. Those helpers perform their owner, inode permission and LSM checks using the current ksmbd worker credentials.
Run the complete SET_INFO dispatch with the credentials captured when the handle was opened. This also removes the separate security information credential setup and keeps all SET_INFO classes under one credential scope.
Direct override_creds() is used because it can nest with the request credential overrides already used by rename and link helpers.
Which versions are affected by CVE-2026-64393?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64393?
Apply the vendor's patch.
Is CVE-2026-64393 being exploited?
There is no known exploitation of CVE-2026-64393 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64393, DEBIAN-CVE-2026-64393, GHSA-r5f9-v87x-9739, ROOT-OS-DEBIAN-12-CVE-2026-64393, ROOT-OS-UBUNTU-2204-CVE-2026-64393, UBUNTU-CVE-2026-64393.