CVE-2026-53085 bpf: fix mm lifecycle in open-coded task_vma iterator
A use-after-free in the Linux kernel BPF task_vma iterator allows attackers to execute arbitrary code or escalate privileges via concurrent task exit.
- 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-2026-53085?
CVE-2026-53085 is a high-severity use after free vulnerability in Linux kernel, published on 24 Jun 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:
bpf: fix mm lifecycle in open-coded task_vma iterator
The open-coded task_vma iterator reads task->mm locklessly and acquires mmap_read_trylock() but never calls mmget(). If the task exits concurrently, the mm_struct can be freed as it is not SLAB_TYPESAFE_BY_RCU, resulting in a use-after-free.
Safely read task->mm with a trylock on alloc_lock and acquire an mm reference. Drop the reference via bpf_iter_mmput_async() in _destroy() and error paths. bpf_iter_mmput_async() is a local wrapper around mmput_async() with a fallback to mmput() on !CONFIG_MMU.
Reject irqs-disabled contexts (including NMI) up front. Operations used by _next() and _destroy() (mmap_read_unlock, bpf_iter_mmput_async) take spinlocks with IRQs disabled (pool->lock, pi_lock). Running from NMI or from a tracepoint that fires with those locks held could deadlock.
A trylock on alloc_lock is used instead of the blocking task_lock() (get_task_mm) to avoid a deadlock when a softirq BPF program iterates a task that already holds its alloc_lock on the same CPU.
Which versions are affected by CVE-2026-53085?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53085?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-53085 being exploited?
There is no known exploitation of CVE-2026-53085 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53085, DEBIAN-CVE-2026-53085, GHSA-44fh-c439-xq8f, ROOT-OS-UBUNTU-2404-CVE-2026-53085, UBUNTU-CVE-2026-53085.