CVE-2026-64156

A flaw was found in the Linux kernel's network file system (netfs) and AFS (Andrew File System) components. When a write operation is skipped due to lock contention and a specific writeback control flag (WB_SYNC_NONE), the system may fail to correctly re-mark the inode, which is a data structure that stores information about a file or directory. While currently considered theoretical for directories, this could potentially lead to data inconsistency or other unexpected behavior within the file system.

This vulnerability is rated as having Moderate impact because triggering it requires local file access under specific asynchronous writeback race conditions, primarily leading to localized file system inconsistency rather than direct privilege escalation or data disclosure. The flawed writeback handling in the netfs subsystem requires concurrent lock contention on directory or symlink operations, a scenario that is largely theoretical in production workloads due to existing internal locking serialization. Furthermore, enterprise deployments running Red Hat Enterprise Linux 8 and 9 do not include the vulnerable implementation, restricting potential risk to environments utilizing newer kernel versions with affected network file system configurations.

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 don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.