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CVE-2026-80923
xhci: dbgtty: Fix unregister on tty_register_driver() failure
Published 2026-09-09 (39 days ago) by the Linux kernel CNA. Subsystem drivers/usb. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-80923 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixed | 6.1.187-1 | Update the kernel and reboot. Fixed in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.13-1 | Update the kernel and reboot. Fixed in 7.1.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.13-1 | Update the kernel and reboot. Fixed in 7.1.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
If tty_register_driver() fails, it drops the reference, but fails to set the global dbc_tty_driver to NULL, causing the unregister to be called again when module exits. On module unload dbc_tty_exit() only gates its cleanup on the driver pointer being non-NULL, so it operates on the already-freed driver: module_init(xhci_hcd_init) xhci_hcd_init() xhci_dbc_init() [return value ignored] dbc_tty_init() tty_register_driver() fails tty_driver_kref_put() -> driver freed (dbc_tty_driver left dangling) ... module_exit(xhci_hcd_fini) xhci_hcd_fini() xhci_dbc_exit() dbc_tty_exit() if (dbc_tty_driver) -> true (dangling) tty_unregister_driver() -> use-after-free
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/usb/host/xhci-dbgtty.c
- What this is
- USB XHCI DRIVERMAINTAINERS section matched on drivers/usb/host/xhci* · linux-usb@vger.kernel.org · Supported
Check it on the machine
grep -wE 'CONFIG_OF|CONFIG_PCI|CONFIG_USB|CONFIG_USB_EHCI_HCD|CONFIG_USB_FHCI_HCD|CONFIG_USB_FOTG210_HCD|CONFIG_USB_FSL_USB2|CONFIG_USB_GADGET|CONFIG_USB_ISP116X_HCD|CONFIG_USB_ISP1362_HCD|CONFIG_USB_MAX3421_HCD|CONFIG_USB_OHCI_HCD|CONFIG_USB_PCI|CONFIG_USB_PHY|CONFIG_USB_R8A66597_HCD|CONFIG_USB_SL811_HCD|CONFIG_USB_SUPPORT|CONFIG_USB_U132_HCD|CONFIG_USB_UHCI_HCD|CONFIG_USB_XEN_HCD|CONFIG_USB_XHCI_HCD' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian does not build this code. In 5 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.
- bookworm, trixie, forky, sid, bookworm · linux-6.12n
- n
- not enabled on any flavour - this release does not build the code
- Build switches
- CONFIG_OF, CONFIG_PCI, CONFIG_USB, CONFIG_USB_EHCI_HCD, CONFIG_USB_FHCI_HCD, CONFIG_USB_FOTG210_HCD, CONFIG_USB_FSL_USB2, CONFIG_USB_GADGET, CONFIG_USB_ISP116X_HCD, CONFIG_USB_ISP1362_HCD, CONFIG_USB_MAX3421_HCD, CONFIG_USB_OHCI_HCD, CONFIG_USB_PCI, CONFIG_USB_PHY, CONFIG_USB_R8A66597_HCD, CONFIG_USB_SL811_HCD, CONFIG_USB_SUPPORT, CONFIG_USB_U132_HCD, CONFIG_USB_UHCI_HCD, CONFIG_USB_XEN_HCD, CONFIG_USB_XHCI_HCD
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-09 (39 days ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.17%, higher than 5.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/usb
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.9 | 5.15.220 | 01b7bc093806 |
| 5.9 | 6.1.187 | 43635ff6401c |
| 5.9 | 6.6.156 | eaca2814f32b |
| 5.9 | 6.12.108 | 943f976c93e7 |
| 5.9 | 6.18.49 | 0d0faf3cc44c |
| 5.9 | 7.1.13 | 33ed35ca6294 |
| 5.9 | 7.2.3 | 0e469b94fbba |
| 5.9 | 7.3 | a916fa66a43e |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2026-80923, which is why it is shown as unrated rather than given an invented score. 6,405 of the 20,413 CVEs here carry reasoning; this is not one of them.