# CVE-2024-46735: ublk_drv: fix NULL pointer dereference in ublk_ctrl_start_recovery()

> A local attacker can trigger a kernel crash by submitting duplicate recovery commands to the ublk driver, causing a denial of service.

- **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:** 18 Sep 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2024-46735, DEBIAN-CVE-2024-46735, GHSA-h642-rg9x-ww4c, UBUNTU-CVE-2024-46735

## What is CVE-2024-46735?

CVE-2024-46735 is a medium-severity vulnerability in Linux kernel, published on 18 Sep 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:

ublk_drv: fix NULL pointer dereference in ublk_ctrl_start_recovery()

When two UBLK_CMD_START_USER_RECOVERY commands are submitted, the
first one sets 'ubq->ubq_daemon' to NULL, and the second one triggers
WARN in ublk_queue_reinit() and subsequently a NULL pointer dereference
issue.

Fix it by adding the check in ublk_ctrl_start_recovery() and return
immediately in case of zero 'ub->nr_queues_ready'.

  BUG: kernel NULL pointer dereference, address: 0000000000000028
  RIP: 0010:ublk_ctrl_start_recovery.constprop.0+0x82/0x180
  Call Trace:
   <TASK>
   ? __die+0x20/0x70
   ? page_fault_oops+0x75/0x170
   ? exc_page_fault+0x64/0x140
   ? asm_exc_page_fault+0x22/0x30
   ? ublk_ctrl_start_recovery.constprop.0+0x82/0x180
   ublk_ctrl_uring_cmd+0x4f7/0x6c0
   ? pick_next_task_idle+0x26/0x40
   io_uring_cmd+0x9a/0x1b0
   io_issue_sqe+0x193/0x3f0
   io_wq_submit_work+0x9b/0x390
   io_worker_handle_work+0x165/0x360
   io_wq_worker+0xcb/0x2f0
   ? finish_task_switch.isra.0+0x203/0x290
   ? finish_task_switch.isra.0+0x203/0x290
   ? __pfx_io_wq_worker+0x10/0x10
   ret_from_fork+0x2d/0x50
   ? __pfx_io_wq_worker+0x10/0x10
   ret_from_fork_asm+0x1a/0x30
   </TASK>

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2024-46735?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-46735?

Apply the vendor's patch.

## Is CVE-2024-46735 being exploited?

There is no known exploitation of CVE-2024-46735 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-2024-46735 and fix it if it is affected.

What it is: CVE-2024-46735 is a medium-severity vulnerability in Linux kernel, published on 18 Sep 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-2024-46735 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-2024-46735/ (Markdown: https://insights.sbomify.com/CVE-2024-46735/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-46735
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-46735
- OSV: https://osv.dev/vulnerability/CVE-2024-46735

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-46735/
Summaries are generated and may contain mistakes; the official description above is the record.