# CVE-2023-52566: nilfs2: fix potential use after free in nilfs_gccache_submit_read_data()

> A use-after-free vulnerability in the Linux kernel nilfs2 filesystem allows local attackers to potentially execute code or escalate privileges by triggering a specific garbage collection path.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 2 Mar 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-52566, DEBIAN-CVE-2023-52566, GHSA-4c64-w6qg-97qw, UBUNTU-CVE-2023-52566

## What is CVE-2023-52566?

CVE-2023-52566 is a medium-severity use after free vulnerability in Linux kernel, published on 2 Mar 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:

nilfs2: fix potential use after free in nilfs_gccache_submit_read_data()

In nilfs_gccache_submit_read_data(), brelse(bh) is called to drop the
reference count of bh when the call to nilfs_dat_translate() fails.  If
the reference count hits 0 and its owner page gets unlocked, bh may be
freed.  However, bh->b_page is dereferenced to put the page after that,
which may result in a use-after-free bug.  This patch moves the release
operation after unlocking and putting the page.

NOTE: The function in question is only called in GC, and in combination
with current userland tools, address translation using DAT does not occur
in that function, so the code path that causes this issue will not be
executed.  However, it is possible to run that code path by intentionally
modifying the userland GC library or by calling the GC ioctl directly.

[konishi.ryusuke@gmail.com: NOTE added to the commit log]

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-52566?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-52566?

Apply the vendor's patch.

## Is CVE-2023-52566 being exploited?

There is no known exploitation of CVE-2023-52566 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-2023-52566 and fix it if it is affected.

What it is: CVE-2023-52566 is a medium-severity use after free vulnerability in Linux kernel, published on 2 Mar 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-2023-52566 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-2023-52566/ (Markdown: https://insights.sbomify.com/CVE-2023-52566/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52566
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52566
- OSV: https://osv.dev/vulnerability/CVE-2023-52566

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52566/
Summaries are generated and may contain mistakes; the official description above is the record.