# CVE-2026-31412: usb: gadget: f_mass_storage: Fix potential integer overflow in check_command_size_in_blocks()

> A malicious USB host can trigger an integer overflow in the Linux kernel's mass storage gadget driver, potentially leading to memory corruption and privilege escalation.

- **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:** 10 Apr 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-31412, DEBIAN-CVE-2026-31412, GHSA-35q9-fp2v-jhcq, ROOT-OS-DEBIAN-11-CVE-2026-31412, ROOT-OS-DEBIAN-12-CVE-2026-31412, ROOT-OS-DEBIAN-13-CVE-2026-31412, ROOT-OS-UBUNTU-2204-CVE-2026-31412, ROOT-OS-UBUNTU-2404-CVE-2026-31412, UBUNTU-CVE-2026-31412

## What is CVE-2026-31412?

CVE-2026-31412 is a medium-severity vulnerability in Linux kernel, published on 10 Apr 2026. 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:

usb: gadget: f_mass_storage: Fix potential integer overflow in check_command_size_in_blocks()

The `check_command_size_in_blocks()` function calculates the data size
in bytes by left shifting `common->data_size_from_cmnd` by the block
size (`common->curlun->blkbits`). However, it does not validate whether
this shift operation will cause an integer overflow.

Initially, the block size is set up in `fsg_lun_open()` , and the
`common->data_size_from_cmnd` is set up in `do_scsi_command()`. During
initialization, there is no integer overflow check for the interaction
between two variables.

So if a malicious USB host sends a SCSI READ or WRITE command
requesting a large amount of data (`common->data_size_from_cmnd`), the
left shift operation can wrap around. This results in a truncated data
size, which can bypass boundary checks and potentially lead to memory
corruption or out-of-bounds accesses.

Fix this by using the check_shl_overflow() macro to safely perform the
shift and catch any overflows.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-31412?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31412?

Apply the vendor's patch.

## Is CVE-2026-31412 being exploited?

There is no known exploitation of CVE-2026-31412 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-2026-31412 and fix it if it is affected.

What it is: CVE-2026-31412 is a medium-severity vulnerability in Linux kernel, published on 10 Apr 2026. 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-2026-31412 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-2026-31412/ (Markdown: https://insights.sbomify.com/CVE-2026-31412/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31412
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31412
- OSV: https://osv.dev/vulnerability/CVE-2026-31412

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31412/
Summaries are generated and may contain mistakes; the official description above is the record.