# CVE-2026-74456: can: peak_usb: peak_usb_start(): fix double free of transfer buffer on URB submit error

> A double free vulnerability in the Linux kernel peak_usb driver allows attackers to cause denial of service or potentially execute code via URB submit errors.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-96012, BELL-CVE-2026-74456, DEBIAN-CVE-2026-74456, GHSA-crgv-x77w-rh88, UBUNTU-CVE-2026-74456

## What is CVE-2026-74456?

CVE-2026-74456 is a high-severity use after free vulnerability in Linux, published on 15 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:

can: peak_usb: peak_usb_start(): fix double free of transfer buffer on URB submit error

In peak_usb_start(), each RX URB transfer buffer is allocated with kmalloc()
and the URB is flagged URB_FREE_BUFFER so that the final usb_free_urb() also
frees the transfer buffer.

If usb_submit_urb() fails, the error path frees the buffer explicitly with
kfree(buf) and then calls usb_free_urb(urb). Because URB_FREE_BUFFER is set,
usb_free_urb() -> urb_destroy() frees the same buffer a second time, a double
free of the transfer buffer.

  BUG: KASAN: double-free in usb_free_urb.part.0+0x91/0xb0
  Free of addr ffff8881069ccb80 by task trigger.sh/285

  Call Trace:
   kfree+0x113/0x3c0
   usb_free_urb.part.0+0x91/0xb0

Drop the redundant kfree(buf); usb_free_urb() already releases the transfer
buffer. This mirrors commit 03819abbeb11 ("net: usb: lan78xx: Fix double free
issue with interrupt buffer allocation").

## Which versions are affected by CVE-2026-74456?


## How do I fix CVE-2026-74456?

Apply the vendor's patch.

## Is CVE-2026-74456 being exploited?

There is no known exploitation of CVE-2026-74456 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74456 and fix it if it is affected.

What it is: CVE-2026-74456 is a high-severity use after free vulnerability in Linux, published on 15 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-2026-74456 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-2026-74456/ (Markdown: https://insights.sbomify.com/CVE-2026-74456/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74456
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74456
- OSV: https://osv.dev/vulnerability/CVE-2026-74456

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74456/
Summaries are generated and may contain mistakes; the official description above is the record.