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Fencer Vulns
high 7.8

CVE-2026-68200 json

ALSA: timer: don't re-enter an instance callback that is still running

published 2026-08-10 2 mo ago modified 2026-10-19 20 d ago also EUVD-2026-55301

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 6.12.101, 6.18.42, 7.1.6, 7.2
  • linux Debian 13 6.12.101-1
  • linux Debian 14 7.1.6-1
  • linux-6.12 Debian 12 6.12.101-1~deb12u1

debian advisories DEBIAN-CVE-2026-68200

  • linux Ubuntu 26.04 LTS 7.0.0-38.38
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1014.14
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1014.14
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1008.9
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1015.15
  • linux-azure Ubuntu 26.04 LTS 7.0.0-1017.17
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-38.38.1
  • linux-oracle Ubuntu 26.04 LTS 7.0.0-1013.13

ubuntu advisories UBUNTU-CVE-2026-68200

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-687.49.1.el9_8
  • rv RHEL 9 5.14.0-687.49.1.el9_8
  • perf RHEL 9 5.14.0-687.49.1.el9_8
  • rtla RHEL 9 5.14.0-687.49.1.el9_8
  • libperf RHEL 9 5.14.0-687.49.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.49.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.49.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.49.1.el9_8

red hat advisories RHSA-2026:68570RHSA-2026:68507

  • kernel-rt Linux Micro 6.2 6.12.0-160000.38.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1
  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.38.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1.160000.2.23
  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1
  • kernel-azure SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.38.1
  • kernel-obs-qa SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.38.1

suse advisories SUSE-SU-2026:23887-1SUSE-SU-2026:23902-1SUSE-SU-2026:23897-1SUSE-SU-2026:23881-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.38.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.38.1

opensuse advisories openSUSE-SU-2026:21910-1

  • kernel AlmaLinux 10 6.12.0-211.56.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.56.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.56.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.56.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.56.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.56.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.56.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.56.1.el10_2

almalinux advisories ALSA-2026:68507ALSA-2026:68570

  • kernel Rocky Linux 10 6.12.0-211.56.1.el10_2.0.1
  • kernel Rocky Linux 9 5.14.0-687.49.1.el9_8

rocky linux advisories RLSA-2026:68507RLSA-2026:68570

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-68200 updated cvss 7.8

kernel: Linux kernel: ALSA timer use-after-free vulnerability allows privilege escalation

  • Red Hat CodeReady Linux Builder EUS (v.9.6) libperf 5.14.0-570.152.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-570.152.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-570.152.1.el9_6, kernel-debuginfo-common-aarch64 5.14.0-570.152.1.el9_6, kernel-debuginfo-common-ppc64le 5.14.0-570.152.1.el9_6
    fixed: vendor fix RHSA-2026:91492
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.49.1.el9_8, perf 5.14.0-687.49.1.el9_8, rtla 5.14.0-687.49.1.el9_8, python3-perf 5.14.0-687.49.1.el9_8, kernel-devel-matched 5.14.0-687.49.1.el9_8, kernel-64k-devel-matched 5.14.0-687.49.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:68570
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.56.1.el10_2, perf 6.12.0-211.56.1.el10_2, rtla 6.12.0-211.56.1.el10_2, python3-perf 6.12.0-211.56.1.el10_2, kernel-devel-matched 6.12.0-211.56.1.el10_2, kernel-64k-devel-matched 6.12.0-211.56.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:68507
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.113.1.el10_0, perf 6.12.0-55.113.1.el10_0, rtla 6.12.0-55.113.1.el10_0, python3-perf 6.12.0-55.113.1.el10_0, kernel-devel-matched 6.12.0-55.113.1.el10_0, kernel-64k-devel-matched 6.12.0-55.113.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:88687
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) rv 5.14.0-570.152.1.el9_6, perf 5.14.0-570.152.1.el9_6, rtla 5.14.0-570.152.1.el9_6, python3-perf 5.14.0-570.152.1.el9_6, kernel-devel-matched 5.14.0-570.152.1.el9_6, kernel-64k-devel-matched 5.14.0-570.152.1.el9_6, +7 more
    fixed: vendor fix RHSA-2026:91492
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.49.1.el9_8, kernel-64k 5.14.0-687.49.1.el9_8, kernel-core 5.14.0-687.49.1.el9_8, kernel-tools 5.14.0-687.49.1.el9_8, kernel-modules 5.14.0-687.49.1.el9_8, kernel-64k-core 5.14.0-687.49.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:68570
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.56.1.el10_2, kernel-64k 6.12.0-211.56.1.el10_2, kernel-core 6.12.0-211.56.1.el10_2, kernel-tools 6.12.0-211.56.1.el10_2, kernel-modules 6.12.0-211.56.1.el10_2, kernel-64k-core 6.12.0-211.56.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:68507
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.113.1.el10_0, kernel-64k 6.12.0-55.113.1.el10_0, kernel-core 6.12.0-55.113.1.el10_0, kernel-tools 6.12.0-55.113.1.el10_0, kernel-modules 6.12.0-55.113.1.el10_0, kernel-64k-core 6.12.0-55.113.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:88687
show 13 more
  • Red Hat Enterprise Linux BaseOS EUS (v.9.6) kernel 5.14.0-570.152.1.el9_6, kernel-64k 5.14.0-570.152.1.el9_6, kernel-core 5.14.0-570.152.1.el9_6, kernel-tools 5.14.0-570.152.1.el9_6, kernel-modules 5.14.0-570.152.1.el9_6, kernel-64k-core 5.14.0-570.152.1.el9_6, +27 more
    fixed: vendor fix RHSA-2026:91492
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.49.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.49.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.49.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.49.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.49.1.el9_8
    fixed: vendor fix RHSA-2026:68570
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.56.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.56.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.56.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.56.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.56.1.el10_2
    fixed: vendor fix RHSA-2026:68507
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.113.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.113.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.113.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.113.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.113.1.el10_0
    fixed: vendor fix RHSA-2026:88687
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.49.1.el9_8, kernel-rt-64k 5.14.0-687.49.1.el9_8, kernel-rt-core 5.14.0-687.49.1.el9_8, kernel-rt-modules 5.14.0-687.49.1.el9_8, kernel-rt-64k-core 5.14.0-687.49.1.el9_8, kernel-rt-debug-core 5.14.0-687.49.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:68570
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.56.1.el10_2, kernel-rt-64k 6.12.0-211.56.1.el10_2, kernel-rt-core 6.12.0-211.56.1.el10_2, kernel-rt-modules 6.12.0-211.56.1.el10_2, kernel-rt-64k-core 6.12.0-211.56.1.el10_2, kernel-rt-debug-core 6.12.0-211.56.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:68507
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.113.1.el10_0, kernel-rt-64k 6.12.0-55.113.1.el10_0, kernel-rt-core 6.12.0-55.113.1.el10_0, kernel-rt-modules 6.12.0-55.113.1.el10_0, kernel-rt-64k-core 6.12.0-55.113.1.el10_0, kernel-rt-debug-core 6.12.0-55.113.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:88687
  • Red Hat Enterprise Linux Real Time EUS (v.9.6) kernel-rt 5.14.0-570.152.1.el9_6, kernel-rt-64k 5.14.0-570.152.1.el9_6, kernel-rt-core 5.14.0-570.152.1.el9_6, kernel-rt-modules 5.14.0-570.152.1.el9_6, kernel-rt-64k-core 5.14.0-570.152.1.el9_6, kernel-rt-debug-core 5.14.0-570.152.1.el9_6, +14 more
    fixed: vendor fix RHSA-2026:91492
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.49.1.el9_8, kernel-rt-core 5.14.0-687.49.1.el9_8, kernel-rt-modules 5.14.0-687.49.1.el9_8, kernel-rt-debug-core 5.14.0-687.49.1.el9_8, kernel-rt-modules-core 5.14.0-687.49.1.el9_8, kernel-rt-debug-modules 5.14.0-687.49.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:68570
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.56.1.el10_2, kernel-rt-core 6.12.0-211.56.1.el10_2, kernel-rt-modules 6.12.0-211.56.1.el10_2, kernel-rt-debug-core 6.12.0-211.56.1.el10_2, kernel-rt-modules-core 6.12.0-211.56.1.el10_2, kernel-rt-debug-modules 6.12.0-211.56.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:68507
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.113.1.el10_0, kernel-rt-kvm 6.12.0-55.113.1.el10_0, kernel-rt-core 6.12.0-55.113.1.el10_0, kernel-rt-modules 6.12.0-55.113.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.113.1.el10_0, kernel-rt-debug-core 6.12.0-55.113.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:88687
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) kernel-rt 5.14.0-570.152.1.el9_6, kernel-rt-kvm 5.14.0-570.152.1.el9_6, kernel-rt-core 5.14.0-570.152.1.el9_6, kernel-rt-modules 5.14.0-570.152.1.el9_6, kernel-rt-debug-kvm 5.14.0-570.152.1.el9_6, kernel-rt-debug-core 5.14.0-570.152.1.el9_6, +6 more
    fixed: vendor fix RHSA-2026:91492
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more Red Hat Enterprise Linux for NVIDIA 26 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.