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Vulnerability record · CVE-2026-23234 · published 4 March 2026

CVE-2026-23234: Linux kernel use after free vulnerability

Linux · Linux Kernel

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.

7.8 CVSS 3.1 High EPSS 0.12% · top 98.4% CWE-416 · Use after free
7.8CVSS 3.1 base score
0.12%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References
17 Jun 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/0fb58aff0dafd6837cc91f4154f3ed6e020358fa Patch
https://git.kernel.org/stable/c/2f67ff1e15a8a4d0e4ffc6564ab20d03d7398fe9 Patch
https://git.kernel.org/stable/c/505e1c0530db6152cab3feef8e3e4da3d3e358c9 Patch
https://git.kernel.org/stable/c/995030be4ce6338c6ff814583c14166446a64008 Patch
https://git.kernel.org/stable/c/a42f99be8a16b32a0bb91bb6dda212a6ad61be5d Patch
https://git.kernel.org/stable/c/acc2c97fc0005846e5cf11b5ba3189fef130c9b3 Patch
https://git.kernel.org/stable/c/ce2739e482bce8d2c014d76c4531c877f382aa54 Patch
https://git.kernel.org/stable/c/cf4a9e1bc8129eb63fda5f8bdcd8d87f0bd76f42 Patch

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Source: NIST National Vulnerability Database (record CVE-2026-23234), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.