CVE-2025-38696 MIPS: Don't crash in stack_top() for tasks without ABI or vDSO
A null pointer dereference in the MIPS stack_top function causes a kernel crash when kthreads call it, leading to denial of service.
- 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-2025-38696?
CVE-2025-38696 is a medium-severity vulnerability in Debian Debian Linux, published on 4 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:
MIPS: Don't crash in stack_top() for tasks without ABI or vDSO
Not all tasks have an ABI associated or vDSO mapped, for example kthreads never do. If such a task ever ends up calling stack_top(), it will derefence the NULL ABI pointer and crash.
This can for example happen when using kunit:
mips_stack_top+0x28/0xc0 arch_pick_mmap_layout+0x190/0x220 kunit_vm_mmap_init+0xf8/0x138 __kunit_add_resource+0x40/0xa8 kunit_vm_mmap+0x88/0xd8 usercopy_test_init+0xb8/0x240 kunit_try_run_case+0x5c/0x1a8 kunit_generic_run_threadfn_adapter+0x28/0x50 kthread+0x118/0x240 ret_from_kernel_thread+0x14/0x1c
Only dereference the ABI point if it is set.
The GIC page is also included as it is specific to the vDSO. Also move the randomization adjustment into the same conditional.
Weakness: CWE-476
Which versions are affected by CVE-2025-38696?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38696?
Apply the vendor's patch.
Is CVE-2025-38696 being exploited?
There is no known exploitation of CVE-2025-38696 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-66797, BELL-CVE-2025-38696, DEBIAN-CVE-2025-38696, GHSA-5fwx-5j9v-m6cp, ROOT-OS-DEBIAN-11-CVE-2025-38696, ROOT-OS-DEBIAN-12-CVE-2025-38696 and 3 more.