# CVE-2026-93821: PCI: altera: Protect root bus removal with rescan lock

> A race condition in the Linux kernel PCI altera driver allows local attackers to trigger use-after-free errors, potentially causing system crashes or code execution.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 3 Oct 2026
- **Also known as:** AZL-103823, BELL-CVE-2026-93821, DEBIAN-CVE-2026-93821, GHSA-4f4q-pcpx-7p8f, UBUNTU-CVE-2026-93821

## What is CVE-2026-93821?

CVE-2026-93821 is an use after free vulnerability in Linux, published on 24 Sep 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:

PCI: altera: Protect root bus removal with rescan lock

Hold the pci_rescan_remove_lock lock while stopping and removing a root bus
to avoid racing with concurrent rescan or hotplug operations triggered via
sysfs.  Such races may lead to use-after-free issues or system crashes.

[bhelgaas: commit log]

## Which versions are affected by CVE-2026-93821?


## How do I fix CVE-2026-93821?

Apply the vendor's patch.

## Is CVE-2026-93821 being exploited?

There is no known exploitation of CVE-2026-93821 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93821 and fix it if it is affected.

What it is: CVE-2026-93821 is an use after free vulnerability in Linux, published on 24 Sep 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-2026-93821 in the wild and no public exploit code.

Affected product: 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-2026-93821/ (Markdown: https://insights.sbomify.com/CVE-2026-93821/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93821
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93821
- OSV: https://osv.dev/vulnerability/CVE-2026-93821

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93821/
Summaries are generated and may contain mistakes; the official description above is the record.