CVE-2026-74599 mm/ptdump: always stabilise against page table freeing using init_mm
A race condition in Linux kernel ptdump allows local attackers to exploit page table freeing races, potentially leading to privilege escalation or code execution.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74599?
CVE-2026-74599 is a vulnerability in Linux, published on 22 Aug 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/ptdump: always stabilise against page table freeing using init_mm
Previous commits have established the invariant that kernel page table freeing is performed while an mmap read lock on init_mm is held, which fixes races between ptdump and kernel page table freeing over init_mm.
However, x86 and arm64 can perform a ptdump over an mm other than init_mm via ptdump_walk_pgd() and since kernel memory ranges are shared across non-kernel mm's, this means that the race still exists for these cases.
Fix this by acquiring a nested mmap write lock for init_mm in ptdump_walk_pgd().
This is safe as we take this after mmap write locking the mm, and nothing acquires the init_mm lock first before locking an arbitrary mm, so no deadlock is possible.
Also update walk_page_range_debug() to assert that init_mm is write locked, add a comment explaining why and remove some redundant code, and eliminate the unnecessary and confusing invocation of walk_kernel_page_table_range().
We can safely remove the non-NULL check for walk.mm, as the mmap lock asserts would NULL pointer deref if it was (and of course no callers do this).
The first point at which ptdump can race kernel page table freeing is commit b6bdb7517c3d ("mm/vmalloc: add interfaces to free unmapped page table"), so we target this in the Fixes tag.
Which versions are affected by CVE-2026-74599?
How do I fix CVE-2026-74599?
Apply the vendor's patch.
Is CVE-2026-74599 being exploited?
There is no known exploitation of CVE-2026-74599 in the wild and no public exploit code.
Sources
Also known as AZL-97272, BELL-CVE-2026-74599, DEBIAN-CVE-2026-74599, GHSA-w5r5-f3r4-g5m8, UBUNTU-CVE-2026-74599.