CVE-2026-89640
kernel: cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · September 11, 2026
Updated · October 30, 2026
Description
A flaw was found in the Linux kernel's Common Internet File System (CIFS) implementation. When performing a file range remapping operation with a zero length, an integer underflow can occur if the offset exceeds the file size. This can lead to corruption of the byte count in file system control requests, potentially causing unexpected behavior or data integrity issues. The vulnerability is resolved by correctly validating the offset against the file size before calculating the length, preventing the underflow.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
No mitigation is specified in collected source.
CVSS / CWE
CVSS 3.1 · 6.6CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H
CWE-787 · Out-of-bounds Write