SEPTEMBER 14, 2026
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Case File

CVE-2026-89639

HIGH · CVSS 7.1 EPSS 0.12%

Source: NVD + CISA KEV + EPSS · Published 2026-09-11 · Last synced 2026-09-14

CyberRota Analysis

AI-Generated

The vulnerability affects the CIFS (Common Internet File System) implementation in the Linux kernel, specifically in the handling of file truncation operations. The flaw arises from the lack of proper locking mechanisms during the truncation process, which can lead to stale cached data being served to users. Organizations utilizing Linux systems with CIFS should prioritize addressing this issue to mitigate potential data integrity risks.

CVE
CVE-2026-89639
Severity
HIGH
CVSS
7.1
EPSS
0.12%
Linux

Original NVD Description

In the Linux kernel, the following vulnerability has been resolved: cifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC cifs_do_truncate() is invoked from cifs_open() without i_rwsem, so it cannot use cifs_resize_file_locked() to perform a proper fscache cookie resize. Instead, add cifs_invalidate_cache() after cifs_setsize(). cifs_invalidate_cache() calls fscache_invalidate(), which works without holding i_rwsem: it unconditionally increments inval_counter and sets FSCACHE_COOKIE_NO_DATA_TO_READ, ensuring that stale cached data is not served once the cookie is later activated by fscache_use_cookie(). Truncation to zero leaves no valid cached data, making invalidation the correct semantic here.