CVE-2026-80861
usb: xhci: bail out of setup if the controller is inaccessible
Description
In the Linux kernel, the following vulnerability has been resolved: usb: xhci: bail out of setup if the controller is inaccessible xhci_gen_setup() locates the operational registers using the capability length read from the very first register: xhci->op_regs = hcd->regs + HC_LENGTH(readl(&xhci->cap_regs->hc_capbase)); If the controller is dead or has dropped off the bus, that read returns ~0, HC_LENGTH() truncates it to 0xff, and op_regs ends up 0xff bytes past the page-aligned MMIO base, i.e. unaligned. The first access through it, xhci_halt() -> xhci_handshake() reading op_regs->status, is then an unaligned readl() on device memory. arm64 faults on unaligned device accesses, so instead of xhci_handshake() catching the all-ones value and returning -ENODEV, setup oopses: xhci-pci-renesas 0005:08:00.0: Unable to change power state from D3cold to D0, device inaccessible xhci-pci-renesas 0005:08:00.0: xHCI Host Controller xhci-pci-renesas 0005:08:00.0: new USB bus registered, assigned bus number 1 Unable to handle kernel paging request at virtual address ffff80030a770103 ESR = 0x0000000096000021 FSC = 0x21: alignment fault Internal error: Oops: 0000000096000021 [#1] SMP pc : xhci_halt [xhci_hcd] Call trace: xhci_halt xhci_gen_setup xhci_pci_setup usb_add_hcd usb_hcd_pci_probe xhci_pci_common_probe xhci_pci_renesas_probe This was hit with a Renesas uPD720201 that failed to power up ("Unable to change power state from D3cold to D0, device inaccessible") yet still reached the HCD probe path. Read the capability register once, and if it reads back the all-ones value (as xhci_handshake() and xhci_reset() already test for), abort setup with -ENODEV before op_regs is derived from it. Reading it once also avoids re-reading a register that may change under a concurrent hot-removal.
INFO
Published Date :
Sept. 4, 2026, 4:18 p.m.
Last Modified :
Sept. 4, 2026, 4:18 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Read capability register to detect inaccessible controller.
- Abort setup if the controller is inaccessible.
- Update the Linux kernel to the resolved version.
References to Advisories, Solutions, and Tools
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CVE-2026-80861.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-80861 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-80861
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Sep. 04, 2026
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: usb: xhci: bail out of setup if the controller is inaccessible xhci_gen_setup() locates the operational registers using the capability length read from the very first register: xhci->op_regs = hcd->regs + HC_LENGTH(readl(&xhci->cap_regs->hc_capbase)); If the controller is dead or has dropped off the bus, that read returns ~0, HC_LENGTH() truncates it to 0xff, and op_regs ends up 0xff bytes past the page-aligned MMIO base, i.e. unaligned. The first access through it, xhci_halt() -> xhci_handshake() reading op_regs->status, is then an unaligned readl() on device memory. arm64 faults on unaligned device accesses, so instead of xhci_handshake() catching the all-ones value and returning -ENODEV, setup oopses: xhci-pci-renesas 0005:08:00.0: Unable to change power state from D3cold to D0, device inaccessible xhci-pci-renesas 0005:08:00.0: xHCI Host Controller xhci-pci-renesas 0005:08:00.0: new USB bus registered, assigned bus number 1 Unable to handle kernel paging request at virtual address ffff80030a770103 ESR = 0x0000000096000021 FSC = 0x21: alignment fault Internal error: Oops: 0000000096000021 [#1] SMP pc : xhci_halt [xhci_hcd] Call trace: xhci_halt xhci_gen_setup xhci_pci_setup usb_add_hcd usb_hcd_pci_probe xhci_pci_common_probe xhci_pci_renesas_probe This was hit with a Renesas uPD720201 that failed to power up ("Unable to change power state from D3cold to D0, device inaccessible") yet still reached the HCD probe path. Read the capability register once, and if it reads back the all-ones value (as xhci_handshake() and xhci_reset() already test for), abort setup with -ENODEV before op_regs is derived from it. Reading it once also avoids re-reading a register that may change under a concurrent hot-removal. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/80xxx/CVE-2026-80861.json">CVE-2026-80861</a> Added Reference https://git.kernel.org/stable/c/0b31744f70c5e06cce5fb660e02d057a3b9e0e37 Added Reference https://git.kernel.org/stable/c/78203d5b54a40f0e36196ebf31c9c7a380fc8811 Added Reference https://git.kernel.org/stable/c/bf84c6b0264947794fa783c324a6d874ca6657d8