# CVE-2023-53101: ext4: zero i_disksize when initializing the bootloader inode

> A local attacker can trigger a kernel warning and potential denial of service by exploiting an inconsistency in the ext4 bootloader inode initialization.

- **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 May 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-53101, DEBIAN-CVE-2023-53101, GHSA-j8pm-fwxh-cj2q, UBUNTU-CVE-2023-53101

## What is CVE-2023-53101?

CVE-2023-53101 is a medium-severity denial of service vulnerability in Linux kernel, published on 2 May 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:

ext4: zero i_disksize when initializing the bootloader inode

If the boot loader inode has never been used before, the
EXT4_IOC_SWAP_BOOT inode will initialize it, including setting the
i_size to 0.  However, if the "never before used" boot loader has a
non-zero i_size, then i_disksize will be non-zero, and the
inconsistency between i_size and i_disksize can trigger a kernel
warning:

 WARNING: CPU: 0 PID: 2580 at fs/ext4/file.c:319
 CPU: 0 PID: 2580 Comm: bb Not tainted 6.3.0-rc1-00004-g703695902cfa
 RIP: 0010:ext4_file_write_iter+0xbc7/0xd10
 Call Trace:
  vfs_write+0x3b1/0x5c0
  ksys_write+0x77/0x160
  __x64_sys_write+0x22/0x30
  do_syscall_64+0x39/0x80

Reproducer:
 1. create corrupted image and mount it:
       mke2fs -t ext4 /tmp/foo.img 200
       debugfs -wR "sif <5> size 25700" /tmp/foo.img
       mount -t ext4 /tmp/foo.img /mnt
       cd /mnt
       echo 123 > file
 2. Run the reproducer program:
       posix_memalign(&buf, 1024, 1024)
       fd = open("file", O_RDWR | O_DIRECT);
       ioctl(fd, EXT4_IOC_SWAP_BOOT);
       write(fd, buf, 1024);

Fix this by setting i_disksize as well as i_size to zero when
initiaizing the boot loader inode.

## Which versions are affected by CVE-2023-53101?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53101?

Apply the vendor's patch.

## Is CVE-2023-53101 being exploited?

There is no known exploitation of CVE-2023-53101 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-2023-53101 and fix it if it is affected.

What it is: CVE-2023-53101 is a medium-severity denial of service vulnerability in Linux kernel, published on 2 May 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-2023-53101 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-2023-53101/ (Markdown: https://insights.sbomify.com/CVE-2023-53101/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53101
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53101
- OSV: https://osv.dev/vulnerability/CVE-2023-53101

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53101/
Summaries are generated and may contain mistakes; the official description above is the record.