# CVE-2021-47503: scsi: pm80xx: Do not call scsi_remove_host() in pm8001_alloc()

> A null pointer dereference in the Linux kernel's pm80xx SCSI driver causes a system crash during device probe, leading to denial of service.

- **Severity:** Medium 6.2 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 24 May 2024
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2021-47503, UBUNTU-CVE-2021-47503

## What is CVE-2021-47503?

CVE-2021-47503 is a medium-severity vulnerability in Linux kernel, published on 24 May 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: pm80xx: Do not call scsi_remove_host() in pm8001_alloc()

Calling scsi_remove_host() before scsi_add_host() results in a crash:

 BUG: kernel NULL pointer dereference, address: 0000000000000108
 RIP: 0010:device_del+0x63/0x440
 Call Trace:
  device_unregister+0x17/0x60
  scsi_remove_host+0xee/0x2a0
  pm8001_pci_probe+0x6ef/0x1b90 [pm80xx]
  local_pci_probe+0x3f/0x90

We cannot call scsi_remove_host() in pm8001_alloc() because scsi_add_host()
has not been called yet at that point in time.

Function call tree:

  pm8001_pci_probe()
  |
  `- pm8001_pci_alloc()
  |  |
  |  `- pm8001_alloc()
  |     |
  |     `- scsi_remove_host()
  |
  `- scsi_add_host()

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-47503?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47503?

Apply the vendor's patch.

## Is CVE-2021-47503 being exploited?

There is no known exploitation of CVE-2021-47503 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-2021-47503 and fix it if it is affected.

What it is: CVE-2021-47503 is a medium-severity vulnerability in Linux kernel, published on 24 May 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-2021-47503 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-2021-47503/ (Markdown: https://insights.sbomify.com/CVE-2021-47503/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47503
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47503
- OSV: https://osv.dev/vulnerability/CVE-2021-47503

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47503/
Summaries are generated and may contain mistakes; the official description above is the record.