Linux Kernel Namespace Management Vulnerability for PIDFD Mechanism by The Linux Foundation

CVE-2026-89766

What is CVE-2026-89766?

A vulnerability present in the Linux kernel's PIDFD mechanism can lead to improper access control over namespace file descriptors. Specifically, the lack of holding exec_update_lock while performing checks against a target task's credentials can open a window for unauthorized access after an execve() system call occurs on a setuid binary. This can allow an attacker to access sensitive namespace information that should otherwise be protected, potentially leading to privilege escalation or data leakage. The flaw has been addressed by ensuring that both the ptrace access check and the namespace lookup occur under proper locking, thus aligning with the expected security behavior of namespace file systems.

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