CVE-2026-46035 mm/page_alloc: return NULL early from alloc_frozen_pages_nolock() in NMI on UP
A race condition in the Linux kernel memory allocator on uniprocessor systems can cause freelist corruption and system crashes when triggered from NMI context.
- 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-2026-46035?
CVE-2026-46035 is a medium-severity vulnerability in Linux kernel, published on 27 May 2026. 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:
mm/page_alloc: return NULL early from alloc_frozen_pages_nolock() in NMI on UP
On UP kernels (!CONFIG_SMP), spin_trylock() is a no-op that unconditionally succeeds even when the lock is already held. As a result, alloc_frozen_pages_nolock() called from NMI context can re-enter rmqueue() and acquire the zone lock that the interrupted context is already holding, corrupting the freelists.
With CONFIG_DEBUG_SPINLOCK on UP, the following BUG is triggered with the slub_kunit test module:
BUG: spinlock trylock failure on UP on CPU#0, kunit_try_catch/243 [...] Call Trace: <NMI> dump_stack_lvl+0x3f/0x60 do_raw_spin_trylock+0x41/0x50 _raw_spin_trylock+0x24/0x50 rmqueue.isra.0+0x2a9/0xa70 get_page_from_freelist+0xeb/0x450 alloc_frozen_pages_nolock_noprof+0x111/0x1e0 allocate_slab+0x42a/0x500 ___slab_alloc+0xa7/0x4c0 kmalloc_nolock_noprof+0x164/0x310 [...] </NMI>
Fix this by returning NULL early when invoked from NMI on a UP kernel.
Which versions are affected by CVE-2026-46035?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46035?
Apply the vendor's patch.
Is CVE-2026-46035 being exploited?
There is no known exploitation of CVE-2026-46035 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-46035, DEBIAN-CVE-2026-46035, GHSA-cx4p-78xj-392q, UBUNTU-CVE-2026-46035.