CVE-2026-23234
HIGHCVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Description
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid UAF in f2fs_write_end_io() As syzbot reported an use-after-free issue in f2fs_write_end_io(). It is caused by below race condition: loop device umount - worker_thread - loop_process_work - do_req_filebacked - lo_rw_aio - lo_rw_aio_complete - blk_mq_end_request - blk_update_request - f2fs_write_end_io - dec_page_count - folio_end_writeback - kill_f2fs_super - kill_block_super - f2fs_put_super : free(sbi) : get_pages(, F2FS_WB_CP_DATA) accessed sbi which is freed In kill_f2fs_super(), we will drop all page caches of f2fs inodes before call free(sbi), it guarantee that all folios should end its writeback, so it should be safe to access sbi before last folio_end_writeback(). Let's relocate ckpt thread wakeup flow before folio_end_writeback() to resolve this issue.
Analysis
A use-after-free vulnerability in the Linux kernel's f2fs filesystem allows a local attacker with user privileges to trigger memory corruption and crash the system through a race condition between I/O completion and filesystem unmount operations. The vulnerability occurs when a loop device completes write operations concurrently with an unmount that frees filesystem structures still being accessed by pending I/O handlers. …
Sign in for full analysis, threat intelligence, and remediation guidance.
Remediation
Within 7 days: Identify all affected systems and apply vendor patches promptly. If patching is delayed, consider network segmentation to limit exposure.
Sign in for detailed remediation steps.
Priority Score
Vendor Status
Share
External POC / Exploit Code
Leaving vuln.today