CVE-2026-99137
Received Received - Intake

BaseFortify

Publication date: 2026-10-28

Last updated on: 2026-10-28

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: cifs: don't update i_size in cifs_do_truncate without a cached handle If find_writable_file() returns null, cifs_file_flush will return 0 without issuing set_file_size, and the outer 'if (!rc)' block will set i_size to 0 before telling the server to truncate. If the cifs_open() then fails, the inode will have size 0, while the server file is unchanged. Move the netfs_resize_file() and cifs_setsize() into the 'if (cfile)', so they only run after a successful set_file_size. In the no-handle else branch, evict stale pages with truncate_inode_pages before the O_TRUNC open to dispose of old cache pages, and let the open response set the i_size.

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Meta Information

Published
2026-10-28
Last Modified
2026-10-28
Generated
2026-10-28
AI Q&A
2026-10-28
EPSS Evaluated
N/A
NVD
CVE-2026-99137
EUVD
EUVD-2026-111889

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
Linux Linux 110fee6b9bb58a5c50047fc2594d415f741b591e
Linux Linux 110fee6b9bb58a5c50047fc2594d415f741b591e
Linux Linux 110fee6b9bb58a5c50047fc2594d415f741b591e
Linux Linux 6.18

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves incorrect handling of file size updates in the CIFS (Common Internet File System) module. When a file operation fails, the system may incorrectly set the file size to zero on the local system while leaving the server file unchanged. This happens because the code updates the local file size without ensuring a valid file handle exists.

Detection Guidance

This vulnerability is specific to the Linux kernel's CIFS (Common Internet File System) module. Detection requires checking the kernel version and CIFS module behavior. Use commands like 'uname -r' to check the kernel version and 'lsmod | grep cifs' to verify if the CIFS module is loaded. If the kernel version is vulnerable, inspect CIFS-related logs for truncation or file size issues.

Impact Analysis

This vulnerability could lead to data corruption or loss if applications rely on accurate file sizes. Users might see files reported as empty or truncated even though the server version remains intact. It may cause applications to mishandle files, leading to crashes or incorrect operations.

Mitigation Strategies

Update the Linux kernel to a patched version that includes the fix for this CVE. If immediate patching is not possible, consider disabling the CIFS module temporarily using 'modprobe -r cifs' or restrict access to CIFS shares until the kernel is updated.

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