CVE-2026-80765: HID: hyperv: validate initial device info bounds
In the Linux kernel, the following vulnerability has been resolved:
HID: hyperv: validate initial device info bounds
The Hyper-V synthetic HID host supplies SYNTHHIDINITIALDEVICEINFO messages that contain a HID descriptor followed by the report descriptor bytes. mousevsconreceivedeviceinfo() trusts bLength and wDescriptorLength without checking that the received packet contains both byte ranges.
A malformed host or backend message can therefore make the guest read past the received VMBus packet while copying the report descriptor. Pass the received initial-device-info size into the parser and reject descriptor lengths that exceed the packet.
Impact: A malicious Hyper-V host or backend can crash a guest by sending a short initial device-info message with an oversized HID report descriptor length.
Affected Software
Event History
Frequently Asked Questions
Which systems are exposed to this issue?
Linux guests using the Hyper-V synthetic HID device are exposed when their Hyper-V host or backend can send crafted SYNTH_HID_INITIAL_DEVICE_INFO messages. The described attacker is a malicious Hyper-V host or backend.
What does exploitation require?
An attacker must be able to send a short initial device-info message with an oversized HID report descriptor length to the guest. This causes the guest to read beyond the received VMBus packet while copying the report descriptor.
What is the expected impact?
A malicious host or backend can crash the affected Linux guest. The provided information does not describe privilege escalation, data disclosure, or guest-to-host impact.
How can I tell whether a system has the fix?
The fix passes the received initial-device-info size into the parser and rejects descriptor lengths that exceed the packet. Check whether the kernel source or applied stable patch set includes one of the referenced commits.