CVE-2026-74484

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

binfmt_misc: don't let an 'F' entry pin its own instance

An entry registered with 'F' opens its interpreter at registration time

and holds that file until the entry is freed. Any entry nobody removes

by hand only gets closed once the binfmt_misc superblock is shut down.

If the interpreter lives on a mount that keeps that superblock alive the

two pin each other:

binfmt_misc sb -> inode -> entry -> interp_file -> vfsmount -> binfmt_misc sb

TL;DR the file is never closed. Once the mount namespace is gone there

is nothing left to unregister through either.

There are two ways to trigger this bug:

- Point the interpreter at the instance itself. Its files are regular

files owned by the mounter and both bm_get_inode() and

simple_fill_super() leave i_op at empty_iops. So notify_change() falls

back to simple_setattr() and chmod +x works. We never set SB_I_NOEXEC

and so open_exec() accepts it.

- Use the instanc

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References