# 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.

- **Severity:** Not scored
- **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:** Yes
- **Published:** 4 Feb 2026
- **Updated:** 11 May 2026
- **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

## 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.

## Is CVE-2026-23056 being exploited?

There is no known exploitation of CVE-2026-23056 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23056 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-23056 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-23056/ (Markdown: https://insights.sbomify.com/CVE-2026-23056/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23056
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23056
- OSV: https://osv.dev/vulnerability/CVE-2026-23056

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23056/
Summaries are generated and may contain mistakes; the official description above is the record.