# CVE-2024-35887: ax25: fix use-after-free bugs caused by ax25\_ds\_del\_timer

- 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: 2024-05-19 · Updated: 2026-09-14

## Affected

- Linux: version range not reported
- Linux: 2.6.12

## Description

In the Linux kernel, the following vulnerability has been resolved: ax25: fix use-after-free bugs caused by ax25_ds_del_timer When the ax25 device is detaching, the ax25_dev_device_down() calls ax25_ds_del_timer() to cleanup the slave_timer. When the timer handler is running, the ax25_ds_del_timer() that calls del_timer() in it will return directly. As a result, the use-after-free bugs could happen, one of the scenarios is shown below: (Thread 1) | (Thread 2) | ax25_ds_timeout() ax25_dev_device_down() | ax25_ds_del_timer() | del_timer() | ax25_dev_put() //FREE | | ax25_dev-> //USE In order to mitigate bugs, when the device is detaching, use timer_shutdown_sync() to stop the timer.

## 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.
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## 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/28f2d36ac52225a13e020c2589833f1816a0cfc6
- https://git.kernel.org/stable/c/8a912ef5b7c5d14fb41b9a7935d1df5bb87058bf
- https://git.kernel.org/stable/c/74204bf9050f7627aead9875fe4e07ba125cb19b
- https://git.kernel.org/stable/c/c6a368f9c7af4c14b14d390c2543af8001c9bdb9
- https://git.kernel.org/stable/c/fd819ad3ecf6f3c232a06b27423ce9ed8c20da89

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Page: https://cve.now/CVE-2024-35887
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