CVE-2026-23009

CVE-2026-23009 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: xhci: sideband: don't dereference freed ring when removing sideband endpoint xhci_sideband_remove_endpoint() incorrecly assumes that the endpoint is running and has a valid transfer ring. Lianqin reported a crash during suspend/wake-up stress testing, and found the cause to be dereferencing a non-existing transfer ring 'ep->ring' during xhci_sideband_remove_endpoint(). The endpoint and its ring may be in unknown state if this function is called after xHCI was reinitialized in resume (lost power), or if device is being re-enumerated, disconnected or endpoint already dropped. Fix this by both removing unnecessary ring access, and by checking ep->ring exists before dereferencing it. Also make sure endpoint is running before attempting to stop it. Remove the xhci_initialize_ring_info() call during sideband endpoint removal as is it only initializes ring structure enqueue, dequeue and cycle state values to their starting values without changing actual hardware enqueue, dequeue and cycle state. Leaving them out of sync is worse than leaving it as it is. The endpoint will get freed in after this in most usecases. If the (audio) class driver want's to reuse the endpoint after offload then it is up to the class driver to ensure endpoint is properly set up.

Frequently asked questions

What is CVE-2026-23009?
In the Linux kernel, the following vulnerability has been resolved: xhci: sideband: don't dereference freed ring when removing sideband endpoint xhci_sideband_remove_endpoint() incorrecly assumes that the endpoint is running and has a valid transfer ring. Lianqin reported a crash during suspend/wake-up stress testing, and found the cause to be dereferencing a non-existing transfer ring 'ep->ring' during xhci_sideband_remove_endpoint(). The endpoint and its ring may be in unknown state if this function is called after xHCI was reinitialized in resume (lost power), or if device is being re-enumerated, disconnected or endpoint already dropped. Fix this by both removing unnecessary ring access, and by checking ep->ring exists before dereferencing it. Also make sure endpoint is running before attempting to stop it. Remove the xhci_initialize_ring_info() call during sideband endpoint removal as is it only initializes ring structure enqueue, dequeue and cycle state values to their starting values without changing actual hardware enqueue, dequeue and cycle state. Leaving them out of sync is worse than leaving it as it is. The endpoint will get freed in after this in most usecases. If the (audio) class driver want's to reuse the endpoint after offload then it is up to the class driver to ensure endpoint is properly set up.
How severe is CVE-2026-23009?
CVE-2026-23009 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-23009 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-23009?
CVE-2026-23009 primarily affects Linux Linux Kernel. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-23009?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-23009 have an EU (EUVD) identifier?
Yes. CVE-2026-23009 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-4619.
When was CVE-2026-23009 published?
CVE-2026-23009 was published on 2026-01-25 and last updated on 2026-06-17.

References

Affected products (10)

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