CVE-2023-4515 ksmbd: validate command request size
A missing size validation in the Linux kernel's ksmbd SMB server allows attackers to cause a denial of service via malformed command requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-4515?
CVE-2023-4515 is a critical denial of service vulnerability in Linux kernel, published on 16 Aug 2025. 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: validate command request size
In commit 2b9b8f3b68ed ("ksmbd: validate command payload size"), except for SMB2_OPLOCK_BREAK_HE command, the request size of other commands is not checked, it's not expected. Fix it by add check for request size of other commands.
Which versions are affected by CVE-2023-4515?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-4515?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2023-4515 being exploited?
There is no known exploitation of CVE-2023-4515 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-4515, DEBIAN-CVE-2023-4515, GHSA-j2x9-qg6q-8wg7, UBUNTU-CVE-2023-4515.