CVE-2026-89642

/// Technical description

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

cifs: call pagecache_isize_extended() in cifs_setsize() when extending

cifs_setsize() calls truncate_pagecache() but skips

pagecache_isize_extended() on extension. truncate_setsize() shows

the correct pattern:

i_size_write(inode, newsize);

if (newsize > oldsize)

pagecache_isize_extended(inode, oldsize, newsize);

truncate_pagecache(inode, newsize);

pagecache_isize_extended() zeroes the tail of the page straddling old

EOF. Without it, dirty bytes in that region can be written back to

the server, exposing stale data in the newly extended range.

/// 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