# CVE-2021-47183: scsi: lpfc: Fix link down processing to address NULL pointer dereference

> A NULL pointer dereference in the Linux kernel lpfc driver can cause a denial of service during specific Fibre Channel link down transitions.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Apr 2024
- **Updated:** 5 Aug 2026
- **Also known as:** DEBIAN-CVE-2021-47183, GHSA-m7wr-q7cm-56rh, ROOT-OS-DEBIAN-11-CVE-2021-47183, UBUNTU-CVE-2021-47183

## What is CVE-2021-47183?

CVE-2021-47183 is a high-severity vulnerability in Linux kernel, published on 10 Apr 2024. 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:

scsi: lpfc: Fix link down processing to address NULL pointer dereference

If an FC link down transition while PLOGIs are outstanding to fabric well
known addresses, outstanding ABTS requests may result in a NULL pointer
dereference. Driver unload requests may hang with repeated "2878" log
messages.

The Link down processing results in ABTS requests for outstanding ELS
requests. The Abort WQEs are sent for the ELSs before the driver had set
the link state to down. Thus the driver is sending the Abort with the
expectation that an ABTS will be sent on the wire. The Abort request is
stalled waiting for the link to come up. In some conditions the driver may
auto-complete the ELSs thus if the link does come up, the Abort completions
may reference an invalid structure.

Fix by ensuring that Abort set the flag to avoid link traffic if issued due
to conditions where the link failed.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-47183?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47183?

Apply the vendor's patch.

## Is CVE-2021-47183 being exploited?

There is no known exploitation of CVE-2021-47183 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-2021-47183 and fix it if it is affected.

What it is: CVE-2021-47183 is a high-severity vulnerability in Linux kernel, published on 10 Apr 2024. 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-2021-47183 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-2021-47183/ (Markdown: https://insights.sbomify.com/CVE-2021-47183/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47183
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47183
- OSV: https://osv.dev/vulnerability/CVE-2021-47183

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47183/
Summaries are generated and may contain mistakes; the official description above is the record.