CVE-2026-4018
Summary
by MITRE • 07/14/2026
TOCTOU Race Condition in specific trace commands of the TraceEvent() system call could allow an attacker with local access and with the PROCMGR_AID_TRACE ability, to cause information disclosure, data tampering or a crash of the QNX Neutrino kernel.
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Analysis
by VulDB Data Team • 07/14/2026
A critical race condition vulnerability exists within the QNX Neutrino operating system's TraceEvent() system call implementation, specifically affecting certain trace commands that process trace data. This vulnerability stems from a time-of-check to time-of-use pattern where the system performs validation checks on trace command parameters and then subsequently processes those same parameters without revalidating them. The flaw allows an attacker with local access and the PROCMGR_AID_TRACE ability to exploit this temporal window between verification and execution, creating opportunities for malicious manipulation of kernel trace operations.
The technical implementation of this race condition occurs when the TraceEvent() system call receives specific trace commands that involve file or memory operations. During the initial validation phase, the system checks parameter integrity and access permissions before proceeding with trace data processing. However, between this check and actual execution, an attacker can modify the underlying resources or parameters, causing unpredictable behavior in the kernel's trace subsystem. This vulnerability is particularly dangerous because it operates at kernel level where malicious actions can lead to information disclosure, data corruption, or system instability.
The operational impact of this vulnerability extends beyond simple privilege escalation as it can result in complete system compromise when exploited by a local attacker with the appropriate capabilities. An adversary could potentially disclose sensitive kernel memory contents through carefully crafted trace commands that exploit the race condition to read from unauthorized memory regions. Additionally, the vulnerability may enable data tampering operations where trace records are modified during processing, leading to false reporting of system events or corrupted trace data that could mislead forensic analysis. The most severe consequence involves potential system crashes or kernel panics when the race condition causes invalid memory accesses or improper resource handling.
This vulnerability aligns with CWE-367 Time-of-Check to Time-of-Use (TOCTOU) weakness classification, which specifically addresses situations where a system performs validation checks and then uses the validated resources without rechecking their state. The ATT&CK framework would categorize this under privilege escalation techniques using local system access, potentially falling under T1068 Local Privilege Escalation or T1547.001 Account Manipulation. The PROCMGR_AID_TRACE ability represents a specific privilege level that allows processes to manipulate system trace facilities, making this vulnerability particularly concerning for systems where multiple users or processes have access to trace capabilities.
Mitigation strategies should focus on eliminating the race condition through immediate parameter revalidation before processing, implementing proper locking mechanisms during critical sections of trace command execution, and reducing the privileges required for trace operations. System administrators should consider disabling trace functionality when not actively needed, regularly updating QNX Neutrino installations to receive security patches, and implementing monitoring solutions that can detect anomalous trace activity patterns. Additionally, kernel-level hardening measures such as stack canaries, address space layout randomization, and enhanced memory protection mechanisms can help reduce the impact of potential exploitation attempts.