CVE-2026-89560

/// Technical description

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

landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout creation

Whiteout objects are used in the upper layer of an OverlayFS to

indicate that the file with this name does not exist in the unified

view, even if it is present in one of the lower layer file systems.

For the userspace implementations of OverlayFS (fuse-overlayfs),

whiteout objects can be created from userspace as well:

* mknod(2) with S_IFCHR and makedev(0, 0)

* renameat2(2) with RENAME_WHITEOUT,

creating the whiteout in the old place of the moved file.

This commit guards whiteout creation in both of these cases with

LANDLOCK_ACCESS_FS_MAKE_REG. Whiteout objects are *not* considered

character devices and are not bound to a driver.

LANDLOCK_ACCESS_FS_MAKE_REG describes the same permission class as a

whiteout object: creating one is the only S_IFCHR creation that the VFS

exempts from CAP_MKNOD, so it is as unprivileged as creating a regular

file

/// 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