Description
In the Linux kernel, the following vulnerability has been resolved:
ALSA: timer: don't re-enter an instance callback that is still running
The userspace-driven timer (utimer) TRIGGER ioctl calls
snd_timer_interrupt() directly with no serialization, so two threads
triggering the same utimer can run snd_timer_interrupt() on one
snd_timer concurrently.
snd_timer_process_callbacks() drops timer->lock around each instance
callback and marks the in-flight callback with the single
SNDRV_TIMER_IFLG_CALLBACK bit; snd_timer_close_locked() waits on that
bit to drain an in-flight callback before freeing the instance. The bit
cannot represent two concurrent callbacks: when a second interrupt
re-queues an instance whose callback is still running, both run at once,
the first to finish clears the bit, and the close-path drain then frees
the instance (and its callback_data) while the other callback is still
live - a use-after-free reachable by any user able to open
/dev/snd/timer, both via a user timer instance and via a sequencer queue
timer bound to the utimer.
snd_timer_interrupt() sets IFLG_CALLBACK before dropping timer->lock, so
a concurrent interrupt already observes it under the lock. Skip
re-queuing an instance (and its slaves) to the ack/sack list while its
callback is in flight; the accumulated pticks are delivered on the next
tick, so no event is lost.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 6.12 | 6.12.101 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 7.1.6-1 | — |
| Debian 13 | linux | 6.12.101-1 | — |
| Debian 12 | linux-6.12 | 6.12.101-1~deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | linux | 7.0.0-38.38 | USN-8887-1 |
| Ubuntu 26.04 LTS | linux-aws +1 | 7.0.0-1014.14 | USN-8887-1 |
| Ubuntu 26.04 LTS | linux-azure | 7.0.0-1017.17 | USN-8888-1 |
| Ubuntu 26.04 LTS | linux-azure-fde | 7.0.0-1016.16 | USN-8888-1 |
| Ubuntu 26.04 LTS | linux-gke | 7.0.0-1008.9 | USN-8887-1 |
| Ubuntu 26.04 LTS | linux-ibm +1 | 7.0.0-1015.15 | USN-8889-1, USN-8887-1 |
| Ubuntu 26.04 LTS | linux-nvidia | 7.0.0-1025.26 | USN-9043-1 |
| Ubuntu 26.04 LTS | linux-nvidia-bos | 7.0.0-2022.23 | USN-9003-1 |
| Ubuntu 26.04 LTS | linux-oracle | 7.0.0-1013.13 | USN-8887-1 |
| Ubuntu 26.04 LTS | linux-raspi | 7.0.0-1023.23 | USN-9021-1 |
| Ubuntu 26.04 LTS | linux-riscv +1 | 7.0.0-38.38.1 | USN-8887-1 |
| Ubuntu 24.04 LTS | linux-aws-7.0 +1 | 7.0.0-1014.14~24.04.1 | USN-8887-3, USN-8887-2 |
| Ubuntu 24.04 LTS | linux-azure-7.0 | 7.0.0-1017.17~24.04.1 | USN-8888-2 |
| Ubuntu 24.04 LTS | linux-azure-fde-7.0 | 7.0.0-1016.16~24.04.1 | USN-8888-2 |
| Ubuntu 24.04 LTS | linux-hwe-7.0 | 7.0.0-38.38~24.04.4 | USN-8887-3 |
| Ubuntu 24.04 LTS | linux-nvidia-7.0 | 7.0.0-1024.25~24.04.1 | USN-9003-1 |
| Ubuntu 24.04 LTS | linux-oracle-7.0 | 7.0.0-1013.13~24.04.1 | USN-8887-3 |
| Ubuntu 24.04 LTS | linux-riscv +27 | No fix yet | — |
| Ubuntu 24.04 LTS | linux-riscv-7.0 | 7.0.0-38.38.1~24.04.1 | — |
| Ubuntu 22.04 LTS | linux-riscv +32 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +28 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp +14 | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime-6.14 +1 | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | rv +76 | 6.12.0-211.56.1.el10_2 | RHSA-2026:68507 |
| RHEL 9 | rv +75 | 5.14.0-687.49.1.el9_8 | RHSA-2026:68570 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10.0 EUS | rv +77 | 6.12.0-55.113.1.el10_0 | RHSA-2026:88687 |
| RHEL 9.6 EUS | rv +77 | 5.14.0-570.152.1.el9_6 | RHSA-2026:91492 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | rv +74 | 6.12.0-211.56.1.el10_2 | ALSA-2026:68507 |
| AlmaLinux 9 | rv +73 | 5.14.0-687.49.1.el9_8 | ALSA-2026:68570 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | kernel | 6.12.0-211.56.1.el10_2.0.1 | RLSA-2026:68507 |
| Rocky Linux 9 | kernel | 5.14.0-687.49.1.el9_8 | RLSA-2026:68570 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | kernel-64kb +8 | 6.12.0-160000.38.1 | SUSE-SU-2026:23902-1 |
| SLES for SAP 16.0 | kernel-default-base | 6.12.0-160000.38.1.160000.2.23 | SUSE-SU-2026:23902-1 |
| SLES 16.0 | kernel-64kb +8 | 6.12.0-160000.38.1 | SUSE-SU-2026:23902-1, SUSE-SU-2026:23897-1 |
| SLES 16.0 | kernel-default-base | 6.12.0-160000.38.1.160000.2.23 | SUSE-SU-2026:23902-1 |
| SLE Micro 6.2 | kernel-default-base | 6.12.0-160000.38.1.160000.2.23 | SUSE-SU-2026:23887-1 |
| SLE Micro 6.2 | kernel-rt +5 | 6.12.0-160000.38.1 | SUSE-SU-2026:23887-1, SUSE-SU-2026:23881-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | kernel-default-base | 6.12.0-160000.38.1.160000.2.22 | openSUSE-SU-2026:21910-1 |
| openSUSE Leap 16.0 | kernel-rt +11 | 6.12.0-160000.38.1 | openSUSE-SU-2026:21910-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | rv +29 | 6.12.0-211.56.1.el10_2 | ELSA-2026-68507 |
| Oracle Linux 9 | kernel-uek +34 | 6.12.0-206.104.3.3.el10uek | ELSA-2026-500374, ELSA-2026-500248 |
| Oracle Linux 9 | rv +28 | 5.14.0-687.49.1.el9_8 | ELSA-2026-68570 |
Advisories 27
- RHSA-2026:91492 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:88687 Red Hat Security Advisory: kernel security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:68570 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:68507 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- USN-9021-1 linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- WID-SEC-2026-2730 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
- USN-9043-1 linux-nvidia vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8887-1 linux, linux-aws, linux-gcp, linux-gke, linux-ibm, linux-oracle, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-9003-1 linux-nvidia-7.0, linux-nvidia-bos vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8887-3 linux-gcp-7.0, linux-hwe-7.0, linux-oracle-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8888-2 linux-azure-7.0, linux-azure-fde-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8888-1 linux-azure, linux-azure-fde vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8887-2 linux-aws-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8889-1 linux-oem-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- ALSA-2026:68507 Important: kernel security, bug fix, and enhancement update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:68570 Important: kernel security, bug fix, and enhancement update AlmaLinux Security Advisories · Oct 29, 2026
- ELSA-2026-500374 Important: Unbreakable Enterprise kernel security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Oct 7, 2026
- SUSE-SU-2026:23902-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 30, 2026
- SUSE-SU-2026:23881-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 30, 2026
- SUSE-SU-2026:23887-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 30, 2026
- SUSE-SU-2026:23897-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 30, 2026
- openSUSE-SU-2026:21910-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 25, 2026
- RLSA-2026:68507 Important: kernel security, bug fix, and enhancement update Rocky Linux Security Advisories · Sep 19, 2026
- RLSA-2026:68570 Important: kernel security, bug fix, and enhancement update Rocky Linux Security Advisories · Sep 19, 2026
- ELSA-2026-68570 Important: kernel security, bug fix, and enhancement update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Sep 18, 2026
- ELSA-2026-68507 Important: kernel security, bug fix, and enhancement update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Sep 17, 2026
- ELSA-2026-500248 Important: Unbreakable Enterprise kernel security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Sep 4, 2026