# CVE-2025-38696: MIPS: Don't crash in stack_top() for tasks without ABI or vDSO

> A null pointer dereference in the MIPS stack_top function causes a kernel crash when kthreads call it, leading to denial of service.

- **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:** 4 Sep 2025
- **Updated:** 23 May 2026
- **Also known as:** AZL-66797, BELL-CVE-2025-38696, DEBIAN-CVE-2025-38696, GHSA-5fwx-5j9v-m6cp, ROOT-OS-DEBIAN-11-CVE-2025-38696, ROOT-OS-DEBIAN-12-CVE-2025-38696, ROOT-OS-UBUNTU-2204-CVE-2025-38696, ROOT-OS-UBUNTU-2404-CVE-2025-38696, UBUNTU-CVE-2025-38696

## What is CVE-2025-38696?

CVE-2025-38696 is a medium-severity vulnerability in Debian Debian Linux, published on 4 Sep 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:

MIPS: Don't crash in stack_top() for tasks without ABI or vDSO

Not all tasks have an ABI associated or vDSO mapped,
for example kthreads never do.
If such a task ever ends up calling stack_top(), it will derefence the
NULL ABI pointer and crash.

This can for example happen when using kunit:

    mips_stack_top+0x28/0xc0
    arch_pick_mmap_layout+0x190/0x220
    kunit_vm_mmap_init+0xf8/0x138
    __kunit_add_resource+0x40/0xa8
    kunit_vm_mmap+0x88/0xd8
    usercopy_test_init+0xb8/0x240
    kunit_try_run_case+0x5c/0x1a8
    kunit_generic_run_threadfn_adapter+0x28/0x50
    kthread+0x118/0x240
    ret_from_kernel_thread+0x14/0x1c

Only dereference the ABI point if it is set.

The GIC page is also included as it is specific to the vDSO.
Also move the randomization adjustment into the same conditional.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-38696?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38696?

Apply the vendor's patch.

## Is CVE-2025-38696 being exploited?

There is no known exploitation of CVE-2025-38696 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-2025-38696 and fix it if it is affected.

What it is: CVE-2025-38696 is a medium-severity vulnerability in Debian Debian Linux, published on 4 Sep 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-2025-38696 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-2025-38696/ (Markdown: https://insights.sbomify.com/CVE-2025-38696/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38696
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38696
- OSV: https://osv.dev/vulnerability/CVE-2025-38696

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38696/
Summaries are generated and may contain mistakes; the official description above is the record.