CVE-2025-39815 RISC-V: KVM: fix stack overrun when loading vlenb
A stack buffer overflow in the Linux kernel's RISC-V KVM module allows attackers to potentially execute arbitrary code or escalate privileges.
- 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-2025-39815?
CVE-2025-39815 is a high-severity memory corruption vulnerability in Linux kernel, published on 16 Sep 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:
RISC-V: KVM: fix stack overrun when loading vlenb
The userspace load can put up to 2048 bits into an xlen bit stack buffer. We want only xlen bits, so check the size beforehand.
Which versions are affected by CVE-2025-39815?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-39815?
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-2025-39815 being exploited?
There is no known exploitation of CVE-2025-39815 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-39815, DEBIAN-CVE-2025-39815, GHSA-xcqh-mv9v-g7fj, ROOT-OS-DEBIAN-13-CVE-2025-39815, ROOT-OS-UBUNTU-2404-CVE-2025-39815, UBUNTU-CVE-2025-39815.