CVE-2026-64043
Received Received - Intake

Race Condition in Linux Kernel OpenVPN Netlink Interface

Vulnerability report for CVE-2026-64043, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ovpn: fix race between deleting interface and adding new peer While deleting an existing ovpn interface, there is a very narrow window where adding a new peer via netlink may cause the netdevice to hang and prevent its unregistration. It may happen during ovpn_dellink(), when all existing peers are freed and the device is queued for deregistration, but a CMD_PEER_NEW message comes in adding a new peer that takes again a reference to the netdev. At this point there is no way to release the device because we are under the assumption that all peers were already released. Fix the race condition by releasing all peers in ndo_uninit(), when the netdevice has already been removed from the netdev list. Also ovpn_peer_add() has now an extra check that forces the function to bail out if the device reg_state is not REGISTERED. This way any incoming CMD_PEER_NEW racing with the interface deletion routine will simply stop before adding the peer. Note that the above check happens while holding the netdev_lock to prevent racing netdev state changes. ovpn_dellink() is now empty and can be removed.

CVSS Scores

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

Attack-Flow Graph

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Executive Summary

This vulnerability is a race condition in the Linux kernel's OpenVPN (ovpn) implementation. It occurs when deleting an OpenVPN interface while simultaneously adding a new peer. The issue causes the network device to hang and prevents proper unregistration because the peer addition takes a reference to the device after peers are freed but before deregistration completes.

Detection Guidance

This vulnerability is specific to the Linux kernel's ovpn module and involves a race condition during interface deletion and peer addition. Detection requires checking kernel logs for netdevice hangs or ovpn-related errors during interface operations. Monitor logs for messages indicating netdevice deregistration failures or peer addition attempts on unregistered devices.

Impact Analysis

This could lead to system instability by causing network interfaces to hang during deletion. It may result in temporary loss of network connectivity or require a system reboot to recover the affected interface. Systems relying on OpenVPN for critical network functions could experience disruptions.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA as it pertains to a race condition in the Linux kernel's OpenVPN implementation. Compliance impacts would depend on how the vulnerability is exploited or mitigated in a specific system configuration.

Mitigation Strategies

Apply the latest kernel update that includes the fix for CVE-2026-64043. If immediate patching is not possible, avoid deleting and recreating ovpn interfaces frequently. Ensure no peer addition operations occur during interface deletion to prevent the race condition.

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