CVE-2026-23234 [High] | Use-After-Free in 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.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-03-05	—	0.03%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-03-05

—

0.03%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.8	3.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	5.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.8

3.1

HIGH

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

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

5.9

[email protected]

OS Trackers for CVE-2026-23234

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2026-23234 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6.	https://security-tracker.debian.org/tracker/CVE-2026-23234
`redhat`	—	—	https://access.redhat.com/security/cve/CVE-2026-23234
`suse`	high	CVE-2026-23234 severity important: SUSE including 30 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 230 product×package rows across 41 product lines (SUSE Linux Enterprise High Availability Extension 15 SP7, SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, … (41 product lines)): Known Not Affected 226, Fixed 4.	https://www.suse.com/security/cve/CVE-2026-23234/
`ubuntu`	medium	CVE-2026-23234 medium priority: Ubuntu including 157 source packages (linux, linux-allwinner-5.19, …), 1256 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): DNE 871, ignored 173, needed 128, released 83, not-affected 1.	https://ubuntu.com/security/CVE-2026-23234

Affected software / configurations for CVE-2026-23234

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 3.13, < 5.10.251	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.11, < 5.15.201	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.16, < 6.1.164	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.2, < 6.6.127	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.7, < 6.12.74	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.13, < 6.18.13	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.19, < 6.19.3	cpe:2.3:o:linux:linux_kernel::::::::

References for CVE-2026-23234

URL	Tags
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

URL

CVE-2026-23234 | f2fs: fix to avoid UAF in f2fs_write_end_io()

Exploit prediction scoring system (EPSS) score for CVE-2026-23234

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23234

Weakness enumeration for CVE-2026-23234

OS Trackers for CVE-2026-23234

Affected software / configurations for CVE-2026-23234

References for CVE-2026-23234