# CVE-2025-22003: can: ucan: fix out of bound read in strscpy() source

> A one-byte out-of-bounds read in the Linux kernel ucan driver allows attackers to potentially disclose adjacent memory contents.

- **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:** 3 Apr 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-59826, BELL-CVE-2025-22003, DEBIAN-CVE-2025-22003, GHSA-2648-xh5w-2w3q, ROOT-OS-UBUNTU-2404-CVE-2025-22003, UBUNTU-CVE-2025-22003

## What is CVE-2025-22003?

CVE-2025-22003 is a medium-severity vulnerability in Linux kernel, published on 3 Apr 2025. 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:

can: ucan: fix out of bound read in strscpy() source

Commit 7fdaf8966aae ("can: ucan: use strscpy() to instead of strncpy()")
unintentionally introduced a one byte out of bound read on strscpy()'s
source argument (which is kind of ironic knowing that strscpy() is meant
to be a more secure alternative :)).

Let's consider below buffers:

  dest[len + 1]; /* will be NUL terminated */
  src[len]; /* may not be NUL terminated */

When doing:

  strncpy(dest, src, len);
  dest[len] = '\0';

strncpy() will read up to len bytes from src.

On the other hand:

  strscpy(dest, src, len + 1);

will read up to len + 1 bytes from src, that is to say, an out of bound
read of one byte will occur on src if it is not NUL terminated. Note
that the src[len] byte is never copied, but strscpy() still needs to
read it to check whether a truncation occurred or not.

This exact pattern happened in ucan.

The root cause is that the source is not NUL terminated. Instead of
doing a copy in a local buffer, directly NUL terminate it as soon as
usb_control_msg() returns. With this, the local firmware_str[] variable
can be removed.

On top of this do a couple refactors:

  - ucan_ctl_payload->raw is only used for the firmware string, so
    rename it to ucan_ctl_payload->fw_str and change its type from u8 to
    char.

  - ucan_device_request_in() is only used to retrieve the firmware
    string, so rename it to ucan_get_fw_str() and refactor it to make it
    directly handle all the string termination logic.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2025-22003?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-22003?

Apply the vendor's patch.

## Is CVE-2025-22003 being exploited?

There is no known exploitation of CVE-2025-22003 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-2025-22003 and fix it if it is affected.

What it is: CVE-2025-22003 is a medium-severity vulnerability in Linux kernel, published on 3 Apr 2025. 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-2025-22003 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-2025-22003/ (Markdown: https://insights.sbomify.com/CVE-2025-22003/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-22003
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-22003
- OSV: https://osv.dev/vulnerability/CVE-2025-22003

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-22003/
Summaries are generated and may contain mistakes; the official description above is the record.