# CVE-2025-68308: can: kvaser_usb: leaf: Fix potential infinite loop in command parsers

> A flaw in the Kvaser USB CAN driver allows a local attacker to cause a system hang via an infinite loop when processing specific USB data.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-72661, BELL-CVE-2025-68308, DEBIAN-CVE-2025-68308, GHSA-qxh5-h6mx-qv45, ROOT-OS-UBUNTU-2204-CVE-2025-68308, ROOT-OS-UBUNTU-2404-CVE-2025-68308, UBUNTU-CVE-2025-68308

## What is CVE-2025-68308?

CVE-2025-68308 is a denial of service vulnerability in Linux, published on 16 Dec 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: kvaser_usb: leaf: Fix potential infinite loop in command parsers

The `kvaser_usb_leaf_wait_cmd()` and `kvaser_usb_leaf_read_bulk_callback`
functions contain logic to zero-length commands. These commands are used
to align data to the USB endpoint's wMaxPacketSize boundary.

The driver attempts to skip these placeholders by aligning the buffer
position `pos` to the next packet boundary using `round_up()` function.

However, if zero-length command is found exactly on a packet boundary
(i.e., `pos` is a multiple of wMaxPacketSize, including 0), `round_up`
function will return the unchanged value of `pos`. This prevents `pos`
to be increased, causing an infinite loop in the parsing logic.

This patch fixes this in the function by using `pos + 1` instead.
This ensures that even if `pos` is on a boundary, the calculation is
based on `pos + 1`, forcing `round_up()` to always return the next
aligned boundary.

## Which versions are affected by CVE-2025-68308?


## How do I fix CVE-2025-68308?

Apply the vendor's patch.

## Is CVE-2025-68308 being exploited?

There is no known exploitation of CVE-2025-68308 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68308 and fix it if it is affected.

What it is: CVE-2025-68308 is a denial of service vulnerability in Linux, published on 16 Dec 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-2025-68308 in the wild and no public exploit code.

Affected product: Linux. 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-2025-68308/ (Markdown: https://insights.sbomify.com/CVE-2025-68308/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68308
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68308
- OSV: https://osv.dev/vulnerability/CVE-2025-68308

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68308/
Summaries are generated and may contain mistakes; the official description above is the record.