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TI-2026-81923 Aliases CVE-2026-99216GHSA-rfjw-g695-7wxh

Linux kernel Hyper-V VMBus keeps connection state on error and exit paths

Priority LOW 22Published · Updated

Key facts

Attack vector
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Privileges required
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User interaction
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Attack complexity
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Impact type
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Confidentiality · integrity · availability
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Fix status
Partial Red Hat: 7 without a fix

No CVSS vector from any source. Fix status from CNA and Red Hat.

Summary

The Linux kernel's Hyper-V VMBus driver forced vmbus_connection.conn_state to DISCONNECTED in two places before calling vmbus_disconnect(). vmbus_initiate_unload() unloads the connection only when conn_state is CONNECTED, so the connection stayed up and the Hyper-V host could keep sending messages or posting VMBus interrupts. The flaw came from commit 74347a99e73ae ("x86/Hyper-V: Unload vmbus channel in hv panic callback"), which left these two resets in place. Red Hat rates it Moderate, and it is not listed in CISA KEV.

Written with Claude Haiku 5.5 from the sources below · 2026-10-31

Description from the CNA

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.

Why it matters now

EPSS 0.00137 3rd percentileScored 2026-11-07
Fix Partial Linux (Linux): 4.20, 5.5, 5.7 +8Red Hat: 7 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux4.19.118 to before 4.20; 5.4.35 to before 5.5; 5.6.7 to before 5.74.20, 5.5, 5.7Patch availableCNA
LinuxLinux5.7 and later5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3Patch availableCNA
  • Linux VendorLinux Affected 4.19.118 to before 4.20; 5.4.35 to before 5.5; 5.6.7 to before 5.7 Fixed in 4.20, 5.5, 5.7 Patch available CNA
  • Linux VendorLinux Affected 5.7 and later Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*——Linux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

Install a Linux kernel with the fix, which is fixed in 4.20, 5.5, 5.7, 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13 and 7.3. Red Hat has no fix planned for RHEL 6 and no fix available yet for RHEL 7, 8, 9 and 10 or OpenShift Container Platform 4 and 5.

Written with Claude Haiku 5.5 from the sources below · 2026-10-31

  • Fix · CNA Linux (Linux) Fixed in 4.20, 5.5, 5.7
  • Fix · CNA Linux (Linux) Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 4AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 5AffectedNo fix yet: Fix deferred

Timeline

  1. 2026-10-28 Threatist record created from CVE-2026-99216
  2. 2026-10-28 Alias added: GHSA-rfjw-g695-7wxh
  3. 2026-10-29 Affected versions changed · Red Hat
  4. 2026-10-29 CVSS score added · Red Hat
  5. 2026-10-30 Fix available: Linux/Linux@2732210132f92aca0622b5134027990a809279d5, Linux/Linux@2939215d57bc8e4189290544fca78f3809ac3ef8, Linux/Linux@2e5ffbf1e41abbf6e02ce28115107938f55ff646 +7 · CNA
  6. 2026-10-30 5 new references · CNA
  7. 2026-10-31 Affected versions changed · Red Hat

References

Other 8

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
See all 21741 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences