# CVE-2025-68194: media: imon: make send_packet() more robust

> A flaw in the Linux kernel imon driver causes hung tasks and system stalls due to infinite USB error retries, requiring a local attacker with physical access to trigger.

- **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:** BELL-CVE-2025-68194, DEBIAN-CVE-2025-68194, GHSA-c97r-q83w-hp2r, ROOT-OS-UBUNTU-2204-CVE-2025-68194, ROOT-OS-UBUNTU-2404-CVE-2025-68194, UBUNTU-CVE-2025-68194

## What is CVE-2025-68194?

CVE-2025-68194 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:

media: imon: make send_packet() more robust

syzbot is reporting that imon has three problems which result in
hung tasks due to forever holding device lock [1].

First problem is that when usb_rx_callback_intf0() once got -EPROTO error
after ictx->dev_present_intf0 became true, usb_rx_callback_intf0()
resubmits urb after printk(), and resubmitted urb causes
usb_rx_callback_intf0() to again get -EPROTO error. This results in
printk() flooding (RCU stalls).

Alan Stern commented [2] that

  In theory it's okay to resubmit _if_ the driver has a robust
  error-recovery scheme (such as giving up after some fixed limit on the
  number of errors or after some fixed time has elapsed, perhaps with a
  time delay to prevent a flood of errors).  Most drivers don't bother to
  do this; they simply give up right away.  This makes them more
  vulnerable to short-term noise interference during USB transfers, but in
  reality such interference is quite rare.  There's nothing really wrong
  with giving up right away.

but imon has a poor error-recovery scheme which just retries forever;
this behavior should be fixed.

Since I'm not sure whether it is safe for imon users to give up upon any
error code, this patch takes care of only union of error codes chosen from
modules in drivers/media/rc/ directory which handle -EPROTO error (i.e.
ir_toy, mceusb and igorplugusb).

Second problem is that when usb_rx_callback_intf0() once got -EPROTO error
before ictx->dev_present_intf0 becomes true, usb_rx_callback_intf0() always
resubmits urb due to commit 8791d63af0cf ("[media] imon: don't wedge
hardware after early callbacks"). Move the ictx->dev_present_intf0 test
introduced by commit 6f6b90c9231a ("[media] imon: don't parse scancodes
until intf configured") to immediately before imon_incoming_packet(), or
the first problem explained above happens without printk() flooding (i.e.
hung task).

Third problem is that when usb_rx_callback_intf0() is not called for some
reason (e.g. flaky hardware; the reproducer for this problem sometimes
prevents usb_rx_callback_intf0() from being called),
wait_for_completion_interruptible() in send_packet() never returns (i.e.
hung task). As a workaround for such situation, change send_packet() to
wait for completion with timeout of 10 seconds.

## Which versions are affected by CVE-2025-68194?


## How do I fix CVE-2025-68194?

Apply the vendor's patch.

## Is CVE-2025-68194 being exploited?

There is no known exploitation of CVE-2025-68194 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68194 and fix it if it is affected.

What it is: CVE-2025-68194 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-2025-68194 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-2025-68194/ (Markdown: https://insights.sbomify.com/CVE-2025-68194/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68194
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68194
- OSV: https://osv.dev/vulnerability/CVE-2025-68194

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68194/
Summaries are generated and may contain mistakes; the official description above is the record.