FreeBSD Kernel Shared Memory Vulnerability Allows Local Privilege Escalation
A Time-Of-Check Time-Of-Use vulnerability in FreeBSD Kernel's shared memory implementation allows local privilege escalation, assigned CVE-2026-58094.
A critical vulnerability has been identified within the shared memory implementation of the FreeBSD Kernel, enabling local privilege escalation. This flaw, designated as CVE-2026-58094, allows an attacker who has already gained the ability to execute low-privileged code on a target system to elevate their privileges to a higher level.
The vulnerability operates on a Time-Of-Check Time-Of-Use (TOCTOU) principle. This means that the system checks for certain conditions or permissions at one point in time, but by the time the action is performed, the conditions may have changed, allowing an attacker to bypass security controls. In this specific case, the shared memory mechanism is susceptible to this type of race condition.
The Zero Day Initiative (ZDI), which disclosed the vulnerability, has assigned it a CVSS score of 7.8, indicating a high severity. This score reflects the potential impact and ease of exploitation, given that the attacker only needs initial low-privileged access.
Exploitation requires an attacker to first compromise a system to the point where they can run their own code, albeit with limited permissions. Once this foothold is established, they can then leverage the TOCTOU vulnerability in the shared memory subsystem to gain administrative or root privileges. This would grant them full control over the affected FreeBSD system.
Details regarding specific affected versions of FreeBSD Kernel have not been extensively detailed in the initial disclosure, but it is understood that systems utilizing the vulnerable shared memory implementation are at risk. Users are advised to consult official FreeBSD security advisories for the most up-to-date information on affected versions and patch availability.
While the vulnerability requires local access, the ability to escalate privileges on a FreeBSD system can have significant consequences. It can allow attackers to access sensitive data, install persistent malware, disrupt system operations, or use the compromised system as a pivot point for further network attacks.
As this vulnerability has been publicly disclosed by ZDI, it is crucial for system administrators to prioritize patching or implementing mitigations as soon as they become available. The CVSS score suggests that this vulnerability could be an attractive target for attackers seeking to gain deeper access to FreeBSD systems.
This discovery highlights the ongoing importance of rigorous security auditing and timely patching of kernel-level components, as flaws in these fundamental parts of an operating system can lead to severe security compromises.