Uninitialized Kernel Stack Data Leak in FreeBSD

Executive Summary

This vulnerability is a kernel stack disclosure issue in FreeBSD's 32-bit compatibility support subsystem (compat32). The compat32 kevent() handler fails to zero a stack-declared 32-bit struct before translating a 64-bit kevent struct. This can expose uninitialized kernel stack data to unprivileged users, potentially revealing sensitive information.

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Detection Guidance

This vulnerability cannot be directly detected through network scanning or typical commands. It requires checking the FreeBSD version and patch status. Use 'freebsd-version' or 'uname -r' to verify the system version and compare it against patched releases (14.3-RELEASE-pX, 14.4-RELEASE-pX, or 15.0-RELEASE-pX).

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Impact Analysis

An unprivileged user could observe a small amount of uninitialized kernel stack data, which may contain sensitive information such as passwords, encryption keys, or other confidential data. This could lead to information disclosure and potential security breaches.

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Compliance Impact

This vulnerability could lead to unauthorized disclosure of sensitive data, which may violate compliance requirements under GDPR, HIPAA, or other regulations. Organizations must ensure systems are patched to prevent data leaks that could result in regulatory penalties.

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Mitigation Strategies

Upgrade affected FreeBSD systems to patched versions (14.3-RELEASE-pX, 14.4-RELEASE-pX, or 15.0-RELEASE-pX) using pkg, freebsd-update, or by recompiling the kernel. Reboot the system after applying updates. No workaround exists; patching is required.

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