# CVE-2026-74680: usb: atm: cxacru: properly kill rcv_urb on error in cxacru_cm()

> A race condition in the Linux kernel cxacru USB ATM driver can cause a kernel warning and potential denial of service when handling URB submission errors.

- **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:** 22 Aug 2026
- **Updated:** 22 Aug 2026
- **Also known as:** BELL-CVE-2026-74680, DEBIAN-CVE-2026-74680, GHSA-29mq-wp6x-9hp3, UBUNTU-CVE-2026-74680

## What is CVE-2026-74680?

CVE-2026-74680 is a vulnerability in Linux, published on 22 Aug 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: atm: cxacru: properly kill rcv_urb on error in cxacru_cm()

If cxacru_cm() encounters an error while submitting or waiting for snd_urb,
it aborts and returns the error without killing the already submitted
rcv_urb. This leaves the rcv_urb active.

When this happens during initialization (e.g., in cxacru_atm_start()), the
driver may ignore the error and proceed to call cxacru_poll_status(), which
invokes cxacru_cm() again. Attempting to submit the still-active rcv_urb
triggers a warning in usb_submit_urb():

cxacru 1-1:1.0: send of cm 0x84 failed (-104)
ATM dev 0: cxacru_atm_start: CHIP_ADSL_LINE_START returned -104
------------[ cut here ]------------
URB ffff88812658d200 submitted while active
WARNING: drivers/usb/core/urb.c:379 at usb_submit_urb+0x79/0x18b0
drivers/usb/core/urb.c:379
...
Call Trace:
 <TASK>
 cxacru_cm+0x21a/0xf10 drivers/usb/atm/cxacru.c:631
 cxacru_cm_get_array drivers/usb/atm/cxacru.c:722 [inline]
 cxacru_poll_status+0x178/0x1110 drivers/usb/atm/cxacru.c:828
 cxacru_atm_start+0x185/0x360 drivers/usb/atm/cxacru.c:814
 usbatm_atm_init+0x144/0x3a0 drivers/usb/atm/usbatm.c:927
 usbatm_usb_probe+0x15cb/0x1db0 drivers/usb/atm/usbatm.c:1178
 cxacru_usb_probe+0x17f/0x220 drivers/usb/atm/cxacru.c:1370
...

To fix this, ensure that rcv_urb is properly killed if cxacru_cm() aborts
early. We can safely call usb_kill_urb() on rcv_urb in the error path, as
it is safe to call even if the URB is not active (e.g., if it failed to
submit in the first place, or if it already completed).

## Which versions are affected by CVE-2026-74680?


## How do I fix CVE-2026-74680?

Apply the vendor's patch.

## Is CVE-2026-74680 being exploited?

There is no known exploitation of CVE-2026-74680 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74680 and fix it if it is affected.

What it is: CVE-2026-74680 is a vulnerability in Linux, published on 22 Aug 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-2026-74680 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-2026-74680/ (Markdown: https://insights.sbomify.com/CVE-2026-74680/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74680
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74680
- OSV: https://osv.dev/vulnerability/CVE-2026-74680

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74680/
Summaries are generated and may contain mistakes; the official description above is the record.