CVE Catalog

CVE-2026-99216

Unknown
Published: Translated: NVD NIST

Summary

In the Linux kernel, the Hyper-V (hv) driver incorrectly forces the VMBus connection state to DISCONNECTED before calling vmbus_disconnect(). As a result, vmbus_initiate_unload() does not unload the connection because it only acts when the state is CONNECTED, so the Hyper-V host may continue sending messages or posting VMBus interrupts.

Risk Assessment

Organizations running Hyper-V virtual machines may experience improper VMBus connection behavior, including continued message processing after shutdown, potentially leading to errors or VM instability.

Recommendation

Update the Linux kernel to a version containing the fix that removes the forced DISCONNECTED state on VMBus exit and error paths.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: Drivers: hv: Don't reset VMBus connection state on error/exit paths In two places, current code forces vmbus_connection.conn_state to DISCONNECTED prior to calling vmbus_disconnect(). But vmbus_disconnect() calls vmbus_initiate_unload(), which unloads the VMBus connection only if the conn_state is CONNECTED. Consequently, the connection remains and the Hyper-V host might continue to send messages or post VMBus interrupts. The problem was introduced in commit 74347a99e73ae ("x86/Hyper-V: Unload vmbus channel in hv panic callback"), in that vmbus_initiate_unload() started checking the current connection state before doing the unload. This commit removed some occurrences where conn_state was forced to DISCONNECTED, but these two remained, apparently due to an oversight at the time. Fix this by not forcing conn_state to DISCONNECTED during VMBus exit, or if a failure occurs when establishing the connection in the first place. Whatever value conn_state has at the time is then read by vmbus_initiate_unload() to determine if there is a connection to be unloaded.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS