CVE-2025-38169 arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP
A race condition in the Linux kernel ARM64 FPSIMD handling can corrupt kernel state, potentially leading to data modification or system crashes.
- 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-2025-38169?
CVE-2025-38169 is a high-severity memory corruption vulnerability in Linux kernel, published on 3 Jul 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:
arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP
On system with SME, a thread's kernel FPSIMD state may be erroneously clobbered during a context switch immediately after that state is restored. Systems without SME are unaffected.
If the CPU happens to be in streaming SVE mode before a context switch to a thread with kernel FPSIMD state, fpsimd_thread_switch() will restore the kernel FPSIMD state using fpsimd_load_kernel_state() while the CPU is still in streaming SVE mode. When fpsimd_thread_switch() subsequently calls fpsimd_flush_cpu_state(), this will execute an SMSTOP, causing an exit from streaming SVE mode. The exit from streaming SVE mode will cause the hardware to reset a number of FPSIMD/SVE/SME registers, clobbering the FPSIMD state.
Fix this by calling fpsimd_flush_cpu_state() before restoring the kernel FPSIMD state.
Which versions are affected by CVE-2025-38169?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-38169?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-38169 being exploited?
There is no known exploitation of CVE-2025-38169 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-38169, DEBIAN-CVE-2025-38169, GHSA-m2xh-87px-jgff, ROOT-OS-UBUNTU-2404-CVE-2025-38169, UBUNTU-CVE-2025-38169.