Linux Kernel Vulnerability in User Namespace and Mount Namespace

CVE-2025-38247

What is CVE-2025-38247?

A vulnerability in the Linux kernel allows for potential information leakage through the mishandling of user namespace and mount namespace references. Specifically, in the function open_tree_attr(2), if a positive result is returned from want_mount_setattr(), it improperly holds on to the mnt_userns without ensuring that finish_mount_kattr() is called. Consequently, a failure in do_mount_setattr() does not adequately clean up, leading to a leak of sensitive namespace information, which could be exploited in certain contexts.

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