CVE-2025-39836 efi: stmm: Fix incorrect buffer allocation method
Incorrect buffer allocation in the Linux kernel EFI STMM driver can cause memory corruption, potentially leading to code execution 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-2025-39836?
CVE-2025-39836 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:
efi: stmm: Fix incorrect buffer allocation method
The communication buffer allocated by setup_mm_hdr() is later on passed to tee_shm_register_kernel_buf(). The latter expects those buffers to be contiguous pages, but setup_mm_hdr() just uses kmalloc(). That can cause various corruptions or BUGs, specifically since commit 9aec2fb0fd5e ("slab: allocate frozen pages"), though it was broken before as well.
Fix this by using alloc_pages_exact() instead of kmalloc().
Weakness: CWE-787
Which versions are affected by CVE-2025-39836?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-39836?
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-2025-39836 being exploited?
There is no known exploitation of CVE-2025-39836 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-39836, DEBIAN-CVE-2025-39836, GHSA-64pc-rqj8-96w6, ROOT-OS-DEBIAN-13-CVE-2025-39836, ROOT-OS-UBUNTU-2404-CVE-2025-39836, UBUNTU-CVE-2025-39836.