CVE-2026-23109

A flaw was found in the Linux kernel's writeback subsystem. The wait_sb_inodes() function waits for all pages under writeback, including those from FUSE filesystems that traditionally do not have data integrity semantics. If a faulty FUSE server fails to reply to write requests, sync operations can hang indefinitely, causing a denial of service.

This regression affects systems using FUSE filesystems where the userspace server may be unresponsive or faulty. The hang occurs during sync() operations and can block system shutdown or other processes waiting for I/O completion. The fix restores the prior behavior where FUSE mappings are skipped during data integrity waits.

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.