# CVE-2024-26844: block: Fix WARNING in _copy_from_iter

> A local attacker can trigger a kernel warning and potential denial of service by crafting specific block device I/O requests with mixed transfer directions.

- **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:** 17 Apr 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2024-26844, DEBIAN-CVE-2024-26844, GHSA-6j6x-q3pw-5hr9, ROOT-OS-DEBIAN-11-CVE-2024-26844, ROOT-OS-UBUNTU-2204-CVE-2024-26844, UBUNTU-CVE-2024-26844

## What is CVE-2024-26844?

CVE-2024-26844 is a medium-severity denial of service vulnerability in Linux kernel, published on 17 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:

block: Fix WARNING in _copy_from_iter

Syzkaller reports a warning in _copy_from_iter because an
iov_iter is supposedly used in the wrong direction. The reason
is that syzcaller managed to generate a request with
a transfer direction of SG_DXFER_TO_FROM_DEV. This instructs
the kernel to copy user buffers into the kernel, read into
the copied buffers and then copy the data back to user space.

Thus the iovec is used in both directions.

Detect this situation in the block layer and construct a new
iterator with the correct direction for the copy-in.

## Which versions are affected by CVE-2024-26844?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-26844?

Apply the vendor's patch.

## Is CVE-2024-26844 being exploited?

There is no known exploitation of CVE-2024-26844 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-2024-26844 and fix it if it is affected.

What it is: CVE-2024-26844 is a medium-severity denial of service vulnerability in Linux kernel, published on 17 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-2024-26844 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-2024-26844/ (Markdown: https://insights.sbomify.com/CVE-2024-26844/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26844
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26844
- OSV: https://osv.dev/vulnerability/CVE-2024-26844

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26844/
Summaries are generated and may contain mistakes; the official description above is the record.