# CVE-2021-47290: scsi: target: Fix NULL dereference on XCOPY completion

> A NULL pointer dereference in the Linux kernel SCSI target module allows local attackers to cause a system crash via EXTENDED COPY commands.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 May 2024
- **Updated:** 5 Aug 2026
- **Also known as:** GHSA-xqq2-v4rf-49qr, UBUNTU-CVE-2021-47290

## What is CVE-2021-47290?

CVE-2021-47290 is a high-severity vulnerability in Linux kernel, published on 21 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

scsi: target: Fix NULL dereference on XCOPY completion

CPU affinity control added with commit 39ae3edda325 ("scsi: target: core:
Make completion affinity configurable") makes target_complete_cmd() queue
work on a CPU based on se_tpg->se_tpg_wwn->cmd_compl_affinity state.

LIO's EXTENDED COPY worker is a special case in that read/write cmds are
dispatched using the global xcopy_pt_tpg, which carries a NULL se_tpg_wwn
pointer following initialization in target_xcopy_setup_pt().

The NULL xcopy_pt_tpg->se_tpg_wwn pointer is dereferenced on completion of
any EXTENDED COPY initiated read/write cmds. E.g using the libiscsi
SCSI.ExtendedCopy.Simple test:

  BUG: kernel NULL pointer dereference, address: 00000000000001a8
  RIP: 0010:target_complete_cmd+0x9d/0x130 [target_core_mod]
  Call Trace:
   fd_execute_rw+0x148/0x42a [target_core_file]
   ? __dynamic_pr_debug+0xa7/0xe0
   ? target_check_reservation+0x5b/0x940 [target_core_mod]
   __target_execute_cmd+0x1e/0x90 [target_core_mod]
   transport_generic_new_cmd+0x17c/0x330 [target_core_mod]
   target_xcopy_issue_pt_cmd+0x9/0x60 [target_core_mod]
   target_xcopy_read_source.isra.7+0x10b/0x1b0 [target_core_mod]
   ? target_check_fua+0x40/0x40 [target_core_mod]
   ? transport_complete_task_attr+0x130/0x130 [target_core_mod]
   target_xcopy_do_work+0x61f/0xc00 [target_core_mod]

This fix makes target_complete_cmd() queue work on se_cmd->cpuid if
se_tpg_wwn is NULL.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-47290?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47290?

No fix has been published for CVE-2021-47290 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-47290 being exploited?

There is no known exploitation of CVE-2021-47290 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-2021-47290 and fix it if it is affected.

What it is: CVE-2021-47290 is a high-severity vulnerability in Linux kernel, published on 21 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-47290 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-2021-47290/ (Markdown: https://insights.sbomify.com/CVE-2021-47290/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47290
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47290
- OSV: https://osv.dev/vulnerability/CVE-2021-47290

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47290/
Summaries are generated and may contain mistakes; the official description above is the record.