# CVE-2023-52486: drm: Don't unref the same fb many times by mistake due to deadlock handling

> A use-after-free vulnerability in the Linux kernel DRM subsystem allows attackers to cause denial of service or potentially execute code via improper framebuffer reference counting during deadlock handling.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/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:** Not needed
- **Fix available:** Yes
- **Published:** 29 Feb 2024
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2023-52486, DEBIAN-CVE-2023-52486, GHSA-ph55-5xqf-59r7, UBUNTU-CVE-2023-52486

## What is CVE-2023-52486?

CVE-2023-52486 is a high-severity use after free vulnerability in Linux kernel, published on 29 Feb 2024. 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:

drm: Don't unref the same fb many times by mistake due to deadlock handling

If we get a deadlock after the fb lookup in drm_mode_page_flip_ioctl()
we proceed to unref the fb and then retry the whole thing from the top.
But we forget to reset the fb pointer back to NULL, and so if we then
get another error during the retry, before the fb lookup, we proceed
the unref the same fb again without having gotten another reference.
The end result is that the fb will (eventually) end up being freed
while it's still in use.

Reset fb to NULL once we've unreffed it to avoid doing it again
until we've done another fb lookup.

This turned out to be pretty easy to hit on a DG2 when doing async
flips (and CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y). The first symptom I
saw that drm_closefb() simply got stuck in a busy loop while walking
the framebuffer list. Fortunately I was able to convince it to oops
instead, and from there it was easier to track down the culprit.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2023-52486?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-52486?

Apply the vendor's patch.

## Is CVE-2023-52486 being exploited?

There is no known exploitation of CVE-2023-52486 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-2023-52486 and fix it if it is affected.

What it is: CVE-2023-52486 is a high-severity use after free vulnerability in Linux kernel, published on 29 Feb 2024. 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-2023-52486 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-2023-52486/ (Markdown: https://insights.sbomify.com/CVE-2023-52486/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52486
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52486
- OSV: https://osv.dev/vulnerability/CVE-2023-52486

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52486/
Summaries are generated and may contain mistakes; the official description above is the record.