CVE-2026-68448

/// Technical description

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

ovl: check access to copy_file_range source with src mounter creds

Commit 5dae222a5ff0c ("vfs: allow copy_file_range to copy across devices")

allowed filesystems that implement the copy_file_range() f_op to decide

if they want to access cross-sb copy from/to the same fs type.

The same commit added checks to verify same sb copy for filesystems that

implement ->copy_file_range() and do not support cross-sb copy at the

time, namely, to ceph, fuse and nfs.

The two remaining fs which implement ->copy_file_range(), cifs and

overlayfs started to support cross-sb copy from this time.

While overlayfs does support cross-sb copy when the two underlying files

are on the same base fs, the copy operation on the two real files from

two different overalyfs filesystems is performed with the mounter

creds of the destination overlayfs and the read permission access hook

for the source file was called with the wrong creds.

This coul

/// 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