CVE-2026-97610

A flaw was found in the Linux kernel's netfs (network filesystem) subsystem. A local user can cause a Denial of Service (DoS) or unexpected system behavior during synchronous unbuffered write operations on network filesystems, such as CIFS (Common Internet File System). When an initial write preparation step fails or an empty data iterator is encountered, the kernel exits early without initializing a return variable. Consequently, an arbitrary value is returned instead of the actual error status, resulting in incorrect error handling and potential system instability.

A moderate impact flaw was found in the Linux kernel's netfs (network filesystem) subsystem. In netfs_unbuffered_write(), the return value variable is left uninitialized when preparation of the first subrequest fails or when an empty data iterator is encountered. As a result, a synchronous unbuffered write operation - reachable through CIFS, for example when cifs_prepare_write() fails to reopen a file or obtain credits - can return an unrelated error or an incorrect value instead of the actual write error status. A local user able to perform write operations on a mounted network filesystem could use this to cause incorrect error handling, unexpected system behavior, or a denial of service. Red Hat rated this flaw Moderate (CVSS 3.1: 5.5, AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Most Red Hat Enterprise Linux streams and OpenShift Container Platform releases are not affected because the vulnerable code is not present in their kernels. The kernel in Red Hat Enterprise Linux 10.3 and 10.4 and in Red Hat In-Vehicle OS 2 streams is affected, with the fix deferred in line with the moderate, local, privilege-required nature of the issue; the residual risk while the fix is deferred is incorrect error reporting and possible local denial of service during synchronous unbuffered writes on network filesystems such as CIFS.

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.