# CVE-2026-43497: fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free

> A use-after-free in the udlfb driver allows local attackers to execute code or escalate privileges via stale memory mappings after USB disconnect.

- **Severity:** High 7.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 21 May 2026
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-87071, BELL-CVE-2026-43497, DEBIAN-CVE-2026-43497, GHSA-233x-r9gj-mfg9, ROOT-OS-DEBIAN-11-CVE-2026-43497, ROOT-OS-DEBIAN-12-CVE-2026-43497, ROOT-OS-UBUNTU-2204-CVE-2026-43497, ROOT-OS-UBUNTU-2404-CVE-2026-43497, UBUNTU-CVE-2026-43497

## What is CVE-2026-43497?

CVE-2026-43497 is a high-severity use after free vulnerability in Linux kernel, published on 21 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free

dlfb_ops_mmap() uses remap_pfn_range() to map vmalloc framebuffer pages
to userspace but sets no vm_ops on the VMA. This means the kernel cannot
track active mmaps. When dlfb_realloc_framebuffer() replaces the backing
buffer via FBIOPUT_VSCREENINFO, existing mmap PTEs are not invalidated.
On USB disconnect, dlfb_ops_destroy() calls vfree() on the old pages
while userspace PTEs still reference them, resulting in a use-after-free:
the process retains read/write access to freed kernel pages.

Add vm_operations_struct with open/close callbacks that maintain an
atomic mmap_count on struct dlfb_data. In dlfb_realloc_framebuffer(),
check mmap_count and return -EBUSY if the buffer is currently mapped,
preventing buffer replacement while userspace holds stale PTEs.

Tested with PoC using dummy_hcd + raw_gadget USB device emulation.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-43497?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43497?

Apply the vendor's patch.

## Is CVE-2026-43497 being exploited?

There is no known exploitation of CVE-2026-43497 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43497 and fix it if it is affected.

What it is: CVE-2026-43497 is a high-severity use after free vulnerability in Linux kernel, published on 21 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-43497 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-43497/ (Markdown: https://insights.sbomify.com/CVE-2026-43497/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43497
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43497
- OSV: https://osv.dev/vulnerability/CVE-2026-43497

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43497/
Summaries are generated and may contain mistakes; the official description above is the record.