# CVE-2026-43489: liveupdate: luo_file: remember retrieve() status

> A flaw in the Linux kernel liveupdate module allows use-after-free conditions via repeated retrieve attempts, potentially leading to system crashes or code execution.

- **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:** 13 May 2026
- **Updated:** 13 May 2026
- **Also known as:** DEBIAN-CVE-2026-43489, GHSA-hv64-4pwv-7xc6, UBUNTU-CVE-2026-43489

## What is CVE-2026-43489?

CVE-2026-43489 is a medium-severity use after free vulnerability in Linux kernel, published on 13 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:

liveupdate: luo_file: remember retrieve() status

LUO keeps track of successful retrieve attempts on a LUO file.  It does so
to avoid multiple retrievals of the same file.  Multiple retrievals cause
problems because once the file is retrieved, the serialized data
structures are likely freed and the file is likely in a very different
state from what the code expects.

The retrieve boolean in struct luo_file keeps track of this, and is passed
to the finish callback so it knows what work was already done and what it
has left to do.

All this works well when retrieve succeeds.  When it fails,
luo_retrieve_file() returns the error immediately, without ever storing
anywhere that a retrieve was attempted or what its error code was.  This
results in an errored LIVEUPDATE_SESSION_RETRIEVE_FD ioctl to userspace,
but nothing prevents it from trying this again.

The retry is problematic for much of the same reasons listed above.  The
file is likely in a very different state than what the retrieve logic
normally expects, and it might even have freed some serialization data
structures.  Attempting to access them or free them again is going to
break things.

For example, if memfd managed to restore 8 of its 10 folios, but fails on
the 9th, a subsequent retrieve attempt will try to call
kho_restore_folio() on the first folio again, and that will fail with a
warning since it is an invalid operation.

Apart from the retry, finish() also breaks.  Since on failure the
retrieved bool in luo_file is never touched, the finish() call on session
close will tell the file handler that retrieve was never attempted, and it
will try to access or free the data structures that might not exist, much
in the same way as the retry attempt.

There is no sane way of attempting the retrieve again.  Remember the error
retrieve returned and directly return it on a retry.  Also pass this
status code to finish() so it can make the right decision on the work it
needs to do.

This is done by changing the bool to an integer.  A value of 0 means
retrieve was never attempted, a positive value means it succeeded, and a
negative value means it failed and the error code is the value.

## Which versions are affected by CVE-2026-43489?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43489?

Apply the vendor's patch.

## Is CVE-2026-43489 being exploited?

There is no known exploitation of CVE-2026-43489 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-2026-43489 and fix it if it is affected.

What it is: CVE-2026-43489 is a medium-severity use after free vulnerability in Linux kernel, published on 13 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-2026-43489 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-2026-43489/ (Markdown: https://insights.sbomify.com/CVE-2026-43489/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43489
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43489
- OSV: https://osv.dev/vulnerability/CVE-2026-43489

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43489/
Summaries are generated and may contain mistakes; the official description above is the record.