Uninitialized Memory Exposure in FreeBSD's compat32 Kevent Handler

CVE-2026-49425

What is CVE-2026-49425?

The compat32 kevent() handler in FreeBSD's operating system is vulnerable due to the mishandling of the translation between 64-bit and 32-bit kevent structures. This vulnerability allows an unprivileged user to glean a small amount of uninitialized data from the kernel stack, which may inadvertently expose sensitive information stored in that memory segment. The absence of zeroing out the stack-allocated structure before use increases the risk of data leakage, necessitating immediate attention and remediation for affected versions.

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