CVE-2026-90096

A flaw was found in the Linux kernel's FUSE (Filesystem in Userspace) component. When performing direct writes with the O_APPEND flag, the fuse_direct_write_iter() function incorrectly invalidates the page cache. This can lead to data inconsistency, where concurrent readers may access stale data from the page cache instead of the most recent information written to the file.

A moderate severity flaw was found in the Linux kernel's FUSE (Filesystem in Userspace) component. When an application performs a direct I/O write with the O_APPEND flag, fuse_direct_write_iter() captures the write position before generic_write_checks() adjusts it to end-of-file, so the post-write page cache invalidation targets a stale range instead of the range actually written at EOF. When the file size is not page-aligned, a concurrent buffered reader can fault the tail page back into the page cache during the direct write window and subsequently read stale data instead of the newly appended content, resulting in data inconsistency. Exploiting this race requires local access, with a local user racing an O_APPEND direct write against buffered reads of the same FUSE-mounted file; Red Hat rates this flaw moderate impact (CVSS 3.1: 5.5, AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). All shipped Red Hat Enterprise Linux, Red Hat In-Vehicle OS, and OpenShift Container Platform kernel components are not affected because the vulnerable code is not present in the kernel versions they ship. The Red Hat Enterprise Linux 6 kernel is out of support scope (OOSS).

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 for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.