VulnerabilityPublished 28 Oct 2026

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

Source GCVE Database

Authoritative record:CVE-2026-99216

Not known to be exploited · fixed in f47ce27af80b87cc684d5c12b65506af498ac7e5 : update Linux kernel when convenient.

Data as of 28 Oct 2026, 13:30 UTC

Severity

Low

Rated Low by Threat Radar's AI analysis · CVSS not yet scored by NVD

Patch: Available – fixed in f47ce27af80b87cc684d5c12b65506af498ac7e5, ec31dc39e835ccde0930daccece8c492d28282fc, 3195546a377c2d8d176d837e8baad5ce15d11195 +3

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-rfjw-g695-7wxh

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=4.19.118 <4.20 >=5.4.35 <5.5 >=5.6.7 <5.7	Fixed in f47ce27af80b87cc684d5c12b65506af498ac7e5 ec31dc39e835ccde0930daccece8c492d28282fc 3195546a377c2d8d176d837e8baad5ce15d11195 5.7 5.5 4.20
LinuxLinux	Affected =5.7	Fixed in–
Debiandebian/linux`pkg:deb/debian/linux`Other threats	Affected >=4.19.118 <4.20 >=5.4.35 <5.5 >=5.6.7 <5.7 =5.7	Fixed in 4.20 5.5 5.7

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix has been implemented in the Linux kernel to address this issue by not forcing the VMBus connection state to DISCONNECTED during error or exit paths. Users should apply the official Linux kernel updates that include this fix once available. No additional mitigation steps are indicated.

Description

A vulnerability in the Linux kernel's Hyper-V driver (hv) involves improper resetting of the VMBus connection state on error or exit paths. The issue causes the connection state to be set to DISCONNECTED prematurely, preventing proper unloading of the VMBus connection. This may result in the Hyper-V host continuing to send messages or interrupts after the connection should have been terminated. The flaw was introduced by a commit that changed how connection state was checked before unloading. The fix avoids forcing the connection state to DISCONNECTED during exit or connection failures, allowing proper unload behavior.

Impact

If unpatched, the Hyper-V host may continue to send messages or post VMBus interrupts even after the connection is logically disconnected on the Linux guest side. This could lead to unexpected behavior or resource usage on the guest. There is no indication of direct security compromise such as privilege escalation or code execution from the provided data.

Summary

The Linux kernel hv driver had a flaw where vmbus_connection.conn_state was forcibly set to DISCONNECTED before calling vmbus_disconnect() in two code paths. Since vmbus_disconnect() calls vmbus_initiate_unload(), which only unloads the connection if conn_state is CONNECTED, the connection was not unloaded properly. This caused the Hyper-V host to potentially continue sending messages or posting interrupts despite the connection being logically disconnected. The problem originated from a commit that introduced state checks before unloading but left two instances where conn_state was still forced to DISCONNECTED. The fix removes these forced state changes to ensure vmbus_initiate_unload() correctly unloads the connection based on the actual state.

References

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