CVE-2025-26168: IXON VPN Client Privilege Escalation Flaw

CVE-2025-26168 Overview

CVE-2025-26168 is a local privilege escalation vulnerability in the IXON VPN Client before version 1.4.4 on Linux and macOS. The flaw allows a low-privileged local user to gain root privileges through a race condition affecting a temporary configuration file stored in a world-writable directory. The VPN client executes code from this configuration file, and an attacker who wins the race can overwrite the file before it is consumed by the privileged process. The vulnerability is categorized under CWE-732: Incorrect Permission Assignment for Critical Resource.

Critical Impact
Successful exploitation results in arbitrary code execution as root on affected Linux and macOS endpoints running the IXON VPN Client.

Affected Products

IXON VPN Client versions prior to 1.4.4 on Linux
IXON VPN Client versions prior to 1.4.4 on macOS
Industrial remote access deployments relying on the IXON VPN Client

Discovery Timeline

2025-05-07 - CVE-2025-26168 published to NVD
2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-26168

Vulnerability Analysis

The IXON VPN Client writes a temporary configuration file to a world-writable directory during connection setup. A privileged component of the client subsequently reads this file and executes code derived from its contents. Because the directory permits writes by any local user, an unprivileged attacker can replace or modify the file between its creation and its consumption by the privileged process. This time-of-check to time-of-use (TOCTOU) flaw converts an ordinary local user session into full root execution. The classification under [CWE-732] reflects the unsafe directory permissions that enable the attack.

Root Cause

The root cause is improper permission assignment on the directory used to stage the temporary configuration file. The client trusts the integrity of a file located in a path that any local account can modify. There is no atomic file handling, integrity check, or restricted directory enforcement before the privileged process loads the configuration.

Attack Vector

Exploitation requires local access but no prior authentication to the VPN client itself. An attacker monitors the predictable directory for the temporary configuration file, then races to overwrite it with attacker-controlled content. When the privileged helper reads the file, it executes the injected directives with root authority. The attack complexity is rated high because successful exploitation depends on winning a timing window, but no user interaction is required.

No public proof-of-concept exploit is currently available, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog. Technical specifics on the timing window and configuration directives are described in the IXON VPN Client installation advisory.

Detection Methods for CVE-2025-26168

Indicators of Compromise

Unexpected files appearing in world-writable temporary directories used by the IXON VPN Client process tree
Child processes spawned by the privileged IXON helper that do not correspond to legitimate VPN client binaries
Unauthorized modifications to files under /tmp or equivalent staging paths immediately before VPN client invocation

Detection Strategies

Monitor file creation and modification events in world-writable directories accessed by the IXON VPN Client, correlated against the parent process executing as root
Hunt for non-root processes writing to configuration paths immediately followed by privileged read operations on the same paths
Alert on shell interpreters or scripting engines spawned as children of the IXON VPN Client privileged helper

Monitoring Recommendations

Enable auditd on Linux and Endpoint Security framework telemetry on macOS to capture open, rename, and execve events on IXON client paths
Inventory hosts running the IXON VPN Client and confirm installed versions are at or above 1.4.4
Review historical process execution logs for anomalous root-level commands traceable to the VPN client helper

How to Mitigate CVE-2025-26168

Immediate Actions Required

Upgrade the IXON VPN Client to version 1.4.4 or later on all Linux and macOS endpoints
Restrict local interactive access on systems where the IXON VPN Client is installed until patching is complete
Audit world-writable directories on affected hosts and remove any unauthorized files staged by local users

Patch Information

IXON has released version 1.4.4 of the VPN Client, which addresses the unsafe directory permissions and race condition. Refer to the IXON support article on VPN Client installation and uninstallation for upgrade procedures, and the IXON cloud advisory resource for vendor guidance.

Workarounds

Limit the set of users who can log in locally or via SSH on systems running the IXON VPN Client
Apply stricter permissions on temporary directories used by the client where supported by the host configuration
Disable or uninstall the IXON VPN Client on hosts where it is not actively required until the patched version is deployed

bash

# Verify installed IXON VPN Client version on Linux/macOS
ixon-vpn-client --version

# Example: remove stale temporary files before patching (review path per environment)
sudo find /tmp -maxdepth 2 -name 'ixon*' -perm -o+w -print