# CVE-2026-43106: cachefiles: fix incorrect dentry refcount in cachefiles_cull()

> A reference counting error in the Linux kernel's cachefiles module can lead to use-after-free conditions, potentially causing system crashes or arbitrary code execution.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 6 May 2026
- **Updated:** 5 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-43106, GHSA-frxf-jp28-379q, UBUNTU-CVE-2026-43106

## What is CVE-2026-43106?

CVE-2026-43106 is a high-severity use after free vulnerability in Linux kernel, published on 6 May 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:

cachefiles: fix incorrect dentry refcount in cachefiles_cull()

The patch mentioned below changed cachefiles_bury_object() to expect 2
references to the 'rep' dentry.  Three of the callers were changed to
use start_removing_dentry() which takes an extra reference so in those
cases the call gets the expected references.

However there is another call to cachefiles_bury_object() in
cachefiles_cull() which did not need to be changed to use
start_removing_dentry() and so was not properly considered.
It still passed the dentry with just one reference so the net result is
that a reference is lost.

To meet the expectations of cachefiles_bury_object(), cachefiles_cull()
must take an extra reference before the call.  It will be dropped by
cachefiles_bury_object().

## Which versions are affected by CVE-2026-43106?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43106?

Apply the vendor's patch.

## Is CVE-2026-43106 being exploited?

There is no known exploitation of CVE-2026-43106 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-2026-43106 and fix it if it is affected.

What it is: CVE-2026-43106 is a high-severity use after free vulnerability in Linux kernel, published on 6 May 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-2026-43106 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-2026-43106/ (Markdown: https://insights.sbomify.com/CVE-2026-43106/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43106
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43106
- OSV: https://osv.dev/vulnerability/CVE-2026-43106

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43106/
Summaries are generated and may contain mistakes; the official description above is the record.