VulnerabilityPublished 4 Sep 2026Updated 30 Sep 2026

CVE-2026-80816: Linux kernel · ALSA: FCP: Use a private URB for the notification endpoint

Affects Linux kernelSource GCVE Database

Not known to be exploited.

Data as of 26 Oct 2026, 13:47 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-42j7-3823-x574

What to do

Affected software

Product	Affected	Fixed in
Ubuntu 26.04 LTSlinux`pkg:deb/ubuntu/linux?arch=source&distro=resolute`Other threats	Affected 6.17.0-5.5 – 7.0.0-34.34 22 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1013.13 14 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=resolute`Other threats	Affected 6.17.0-1003.3 – 7.0.0-1014.14 14 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resolute`Other threats	Affected 7.0.0-1003.3 – 7.0.0-1013.13 8 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1013.13 12 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gke`pkg:deb/ubuntu/linux-gke?arch=source&distro=resolute`Other threats	Affected 7.0.0-1002.3 – 7.0.0-1007.8 5 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix has been implemented in the Linux kernel to address this issue by using a private URB for the notification endpoint and properly initializing synchronization variables. Users should update to a Linux kernel version that includes this fix once available.

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: FCP: Use a private URB for the notification endpoint fcp_init_notify() used mixer->urb, which snd_usb_mixer_status_create() allocates for the optional UAC2 status interrupt endpoint and mixer.c kills, resubmits and frees. On a device with that endpoint, fcp_init_notify()'s "already set up" early return fires on the status URB and returns success without doing anything. No FCP notification URB is submitted, and cmd_done is left zeroed because it is initialised past that early return and nowhere else. fcp_init() then issues init1_opcode and wait_for_completion_timeout() would crash adding to the zeroed wait.head. fcp_cleanup_urb() would also kill and free mixer.c's status URB. Use a separate URB in fcp_data, and initialise cmd_done in fcp_init_private() where fcp_data is allocated. fcp_init_notify() is reached again after suspend via fcp_reinit(), and the URB kill path in fcp_notify() completes cmd_done, leaving a stale count that would satisfy the next command's wait before the device ACKs. Use reinit_completion() to clear it.

Impact

The vulnerability could cause kernel crashes during ALSA FCP initialization and lead to stale synchronization states that disrupt device communication. This impacts system stability and reliability when using affected ALSA USB audio devices. No evidence of active exploitation is known.

Summary

The Linux kernel ALSA FCP subsystem had a flaw where fcp_init_notify() reused the mixer->urb allocated for the UAC2 status interrupt endpoint. This caused an early return without submitting the required FCP notification URB and left the cmd_done synchronization variable zeroed and uninitialized. As a result, fcp_init() could crash during wait_for_completion_timeout() due to a zeroed wait head. The cleanup function also improperly freed the shared URB. The vulnerability was fixed by allocating a separate URB in fcp_data, initializing cmd_done in fcp_init_private(), and using reinit_completion() to clear stale completion states, ensuring proper notification URB submission and synchronization.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Sep 2026, 11:53 UTC

Technical details

References

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