# CVE-2026-23002: lib/buildid: use __kernel_read() for sleepable context

> A null pointer dereference in the Linux kernel buildid module can cause a system crash, requiring a kernel patch to resolve.

- **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:** 25 Jan 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-23002, DEBIAN-CVE-2026-23002, GHSA-g95h-2j46-jx6w, UBUNTU-CVE-2026-23002

## What is CVE-2026-23002?

CVE-2026-23002 is a medium-severity vulnerability in Linux kernel, published on 25 Jan 2026. 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:

lib/buildid: use __kernel_read() for sleepable context

Prevent a "BUG: unable to handle kernel NULL pointer dereference in
filemap_read_folio".

For the sleepable context, convert freader to use __kernel_read() instead
of direct page cache access via read_cache_folio().  This simplifies the
faultable code path by using the standard kernel file reading interface
which handles all the complexity of reading file data.

At the moment we are not changing the code for non-sleepable context which
uses filemap_get_folio() and only succeeds if the target folios are
already in memory and up-to-date.  The reason is to keep the patch simple
and easier to backport to stable kernels.

Syzbot repro does not crash the kernel anymore and the selftests run
successfully.

In the follow up we will make __kernel_read() with IOCB_NOWAIT work for
non-sleepable contexts.  In addition, I would like to replace the
secretmem check with a more generic approach and will add fstest for the
buildid code.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-23002?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23002?

Apply the vendor's patch.

## Is CVE-2026-23002 being exploited?

There is no known exploitation of CVE-2026-23002 in the wild and no public exploit code.

Public exploit code:

- https://github.com/George0Papasotiriou/CVE-2026-23002-5G-NAS-Message-Buffer-Overflow-in-gNodeB (github_poc): https://github.com/George0Papasotiriou/CVE-2026-23002-5G-NAS-Message-Buffer-Overflow-in-gNodeB

## 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-2026-23002 and fix it if it is affected.

What it is: CVE-2026-23002 is a medium-severity vulnerability in Linux kernel, published on 25 Jan 2026. 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-2026-23002 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-2026-23002/ (Markdown: https://insights.sbomify.com/CVE-2026-23002/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23002
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23002
- OSV: https://osv.dev/vulnerability/CVE-2026-23002

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23002/
Summaries are generated and may contain mistakes; the official description above is the record.