CVE-2026-99216
Received
Received - Intake
Linux Kernel VMBus Connection State Handling Flaw
Vulnerability report for CVE-2026-99216, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-28
Last updated on: 2026-10-28
Assigner: kernel.org
Description
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Linux | Linux | 74347a99e73ae00b8385f1209aaea193c670f901 |
| Linux | Linux | 74347a99e73ae00b8385f1209aaea193c670f901 |
| Linux | Linux | 74347a99e73ae00b8385f1209aaea193c670f901 |
| Linux | Linux | 5e059fc0f054309036d3f612bc8b0a502ca58545 |
| Linux | Linux | 9f38f7b46de0747c1909e8c557aa21715dce20c5 |
| Linux | Linux | caeeb3787167c884b955404a7e669fd77f267e44 |
| Linux | Linux | 4.19.118 |
| Linux | Linux | 5.4.35 |
| Linux | Linux | 5.6.7 |
| Linux | Linux | 5.7 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
