CVE-2026-23056 uacce: implement mremap in uacce_vm_ops to return -EPERM
A local attacker can trigger a double-free vulnerability in the uacce driver via mremap, potentially leading to privilege escalation or system crash.
- 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-2026-23056?
CVE-2026-23056 is an use after free vulnerability in Linux, published on 4 Feb 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:
uacce: implement mremap in uacce_vm_ops to return -EPERM
The current uacce_vm_ops does not support the mremap operation of vm_operations_struct. Implement .mremap to return -EPERM to remind users.
The reason we need to explicitly disable mremap is that when the driver does not implement .mremap, it uses the default mremap method. This could lead to a risk scenario:
An application might first mmap address p1, then mremap to p2, followed by munmap(p1), and finally munmap(p2). Since the default mremap copies the original vma's vm_private_data (i.e., q) to the new vma, both munmap operations would trigger vma_close, causing q->qfr to be freed twice(qfr will be set to null here, so repeated release is ok).
Which versions are affected by CVE-2026-23056?
How do I fix CVE-2026-23056?
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-2026-23056 being exploited?
There is no known exploitation of CVE-2026-23056 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-23056, DEBIAN-CVE-2026-23056, GHSA-43cv-jpm2-7rcc, ROOT-OS-UBUNTU-2204-CVE-2026-23056, ROOT-OS-UBUNTU-2404-CVE-2026-23056, UBUNTU-CVE-2026-23056.