# CVE-2023-54099: fs: Protect reconfiguration of sb read-write from racing writes

> A race condition in Linux kernel filesystem remounting allows local attackers to bypass read-only protections, potentially leading to privilege escalation or data corruption.

- **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:** 24 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-54099, DEBIAN-CVE-2023-54099, GHSA-vwq3-xpg9-vpx4, UBUNTU-CVE-2023-54099

## What is CVE-2023-54099?

CVE-2023-54099 is a vulnerability in Linux, published on 24 Dec 2025. 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:

fs: Protect reconfiguration of sb read-write from racing writes

The reconfigure / remount code takes a lot of effort to protect
filesystem's reconfiguration code from racing writes on remounting
read-only. However during remounting read-only filesystem to read-write
mode userspace writes can start immediately once we clear SB_RDONLY
flag. This is inconvenient for example for ext4 because we need to do
some writes to the filesystem (such as preparation of quota files)
before we can take userspace writes so we are clearing SB_RDONLY flag
before we are fully ready to accept userpace writes and syzbot has found
a way to exploit this [1]. Also as far as I'm reading the code
the filesystem remount code was protected from racing writes in the
legacy mount path by the mount's MNT_READONLY flag so this is relatively
new problem. It is actually fairly easy to protect remount read-write
from racing writes using sb->s_readonly_remount flag so let's just do
that instead of having to workaround these races in the filesystem code.

[1] https://lore.kernel.org/all/00000000000006a0df05f6667499@google.com/T/

## Which versions are affected by CVE-2023-54099?


## How do I fix CVE-2023-54099?

Apply the vendor's patch.

## Is CVE-2023-54099 being exploited?

There is no known exploitation of CVE-2023-54099 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-54099 and fix it if it is affected.

What it is: CVE-2023-54099 is a vulnerability in Linux, published on 24 Dec 2025. 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-2023-54099 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-2023-54099/ (Markdown: https://insights.sbomify.com/CVE-2023-54099/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-54099
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-54099
- OSV: https://osv.dev/vulnerability/CVE-2023-54099

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-54099/
Summaries are generated and may contain mistakes; the official description above is the record.