SB2026102950 - Incomplete cleanup in Linux kernel hv driver

Description

This security bulletin contains information about 1 vulnerability.

1) Incomplete cleanup (CVE-ID: CVE-2026-99216)

CWE-ID: CWE-459 - Incomplete cleanup

CVSSv4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

The vulnerability allows a local privileged user to leave a VMBus connection active after teardown, potentially disrupting guest operation through continued host messages or interrupts.

The vulnerability exists due to incomplete cleanup in the Linux kernel Hyper-V VMBus driver when handling connection-establishment errors or driver exit. A local privileged user can trigger an affected cleanup path to leave the connection active because vmbus_connection.conn_state is prematurely set to DISCONNECTED, causing vmbus_initiate_unload() to skip unloading the connection and allowing host messages or VMBus interrupts to continue.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/3195546a377c2d8d176d837e8baad5ce15d11195
• https://git.kernel.org/stable/c/ec31dc39e835ccde0930daccece8c492d28282fc
• https://git.kernel.org/stable/c/f47ce27af80b87cc684d5c12b65506af498ac7e5