# CVE-2025-38230: jfs: validate AG parameters in dbMount() to prevent crashes

> A local attacker can cause a kernel crash in the JFS filesystem by providing corrupted metadata, leading to a denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 4 Jul 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2025-38230, DEBIAN-CVE-2025-38230, GHSA-x2w5-5jvp-3p83, ROOT-OS-DEBIAN-11-CVE-2025-38230, ROOT-OS-DEBIAN-12-CVE-2025-38230, ROOT-OS-UBUNTU-2204-CVE-2025-38230, ROOT-OS-UBUNTU-2404-CVE-2025-38230, UBUNTU-CVE-2025-38230

## What is CVE-2025-38230?

CVE-2025-38230 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 4 Jul 2025. 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:

jfs: validate AG parameters in dbMount() to prevent crashes

Validate db_agheight, db_agwidth, and db_agstart in dbMount to catch
corrupted metadata early and avoid undefined behavior in dbAllocAG.
Limits are derived from L2LPERCTL, LPERCTL/MAXAG, and CTLTREESIZE:

- agheight: 0 to L2LPERCTL/2 (0 to 5) ensures shift
  (L2LPERCTL - 2*agheight) >= 0.
- agwidth: 1 to min(LPERCTL/MAXAG, 2^(L2LPERCTL - 2*agheight))
  ensures agperlev >= 1.
  - Ranges: 1-8 (agheight 0-3), 1-4 (agheight 4), 1 (agheight 5).
  - LPERCTL/MAXAG = 1024/128 = 8 limits leaves per AG;
    2^(10 - 2*agheight) prevents division to 0.
- agstart: 0 to CTLTREESIZE-1 - agwidth*(MAXAG-1) keeps ti within
  stree (size 1365).
  - Ranges: 0-1237 (agwidth 1), 0-348 (agwidth 8).

UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:1400:9
shift exponent -335544310 is negative
CPU: 0 UID: 0 PID: 5822 Comm: syz-executor130 Not tainted 6.14.0-rc5-syzkaller #0
Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:231 [inline]
 __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468
 dbAllocAG+0x1087/0x10b0 fs/jfs/jfs_dmap.c:1400
 dbDiscardAG+0x352/0xa20 fs/jfs/jfs_dmap.c:1613
 jfs_ioc_trim+0x45a/0x6b0 fs/jfs/jfs_discard.c:105
 jfs_ioctl+0x2cd/0x3e0 fs/jfs/ioctl.c:131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

## Which versions are affected by CVE-2025-38230?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38230?

Apply the vendor's patch.

## Is CVE-2025-38230 being exploited?

There is no known exploitation of CVE-2025-38230 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-38230 and fix it if it is affected.

What it is: CVE-2025-38230 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 4 Jul 2025. 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-2025-38230 in the wild and no public exploit code.

Affected product: Debian Debian 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-2025-38230/ (Markdown: https://insights.sbomify.com/CVE-2025-38230/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38230
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38230
- OSV: https://osv.dev/vulnerability/CVE-2025-38230

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38230/
Summaries are generated and may contain mistakes; the official description above is the record.