CVE-2025-40193 xtensa: simdisk: add input size check in proc_write_simdisk
A local attacker can cause a kernel crash by passing invalid input to the xtensa simdisk proc write function.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40193?
CVE-2025-40193 is a denial of service vulnerability in Linux, published on 12 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
xtensa: simdisk: add input size check in proc_write_simdisk
A malicious user could pass an arbitrarily bad value to memdup_user_nul(), potentially causing kernel crash.
This follows the same pattern as commit ee76746387f6 ("netdevsim: prevent bad user input in nsim_dev_health_break_write()")
Which versions are affected by CVE-2025-40193?
How do I fix CVE-2025-40193?
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-2025-40193 being exploited?
There is no known exploitation of CVE-2025-40193 in the wild and no public exploit code.
Sources
Also known as AZL-70109, BELL-CVE-2025-40193, DEBIAN-CVE-2025-40193, GHSA-j56r-hrh7-8349, ROOT-OS-DEBIAN-11-CVE-2025-40193, ROOT-OS-DEBIAN-13-CVE-2025-40193 and 3 more.