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

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于f2fs_write_end_io函数存在释放后重用问题。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux e234088758fca3a669ebb1a02d8bf7bf60f0e4ff< 0fb58aff0dafd6837cc91f4154f3ed6e020358fa affected
e234088758fca3a669ebb1a02d8bf7bf60f0e4ff< 2f67ff1e15a8a4d0e4ffc6564ab20d03d7398fe9 affected
e234088758fca3a669ebb1a02d8bf7bf60f0e4ff< 505e1c0530db6152cab3feef8e3e4da3d3e358c9 affected
e234088758fca3a669ebb1a02d8bf7bf60f0e4ff< acc2c97fc0005846e5cf11b5ba3189fef130c9b3 affected
e234088758fca3a669ebb1a02d8bf7bf60f0e4ff< cf4a9e1bc8129eb63fda5f8bdcd8d87f0bd76f42 affected
e234088758fca3a669ebb1a02d8bf7bf60f0e4ff< 995030be4ce6338c6ff814583c14166446a64008 affected
e234088758fca3a669ebb1a02d8bf7bf60f0e4ff< a42f99be8a16b32a0bb91bb6dda212a6ad61be5d affected
e234088758fca3a669ebb1a02d8bf7bf60f0e4ff< ce2739e482bce8d2c014d76c4531c877f382aa54 affected
… +10 more rows
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I. Basic Information for CVE-2026-23234

Vulnerability Information
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Vulnerability Title
f2fs: fix to avoid UAF in f2fs_write_end_io()
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于f2fs_write_end_io函数存在释放后重用问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux e234088758fca3a669ebb1a02d8bf7bf60f0e4ff ~ 0fb58aff0dafd6837cc91f4154f3ed6e020358fa -
Linux Linux 3.13 -

II. Public POCs for CVE-2026-23234

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III. Intelligence Information for CVE-2026-23234

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Patches & Fixes for CVE-2026-23234 (8)

Same Patch Batch · Linux · 2026-03-04 · 9 CVEs total

CVE-2026-23231 7.8 HIGH netfilter: nf_tables: fix use-after-free in nf_tables_addchain()
CVE-2026-23236 7.3 HIGH fbdev: smscufx: properly copy ioctl memory to kernelspace
CVE-2026-23232 Revert "f2fs: block cache/dio write during f2fs_enable_checkpoint()"
CVE-2025-71238 scsi: qla2xxx: Fix bsg_done() causing double free
CVE-2026-23233 f2fs: fix to avoid mapping wrong physical block for swapfile
CVE-2026-23235 f2fs: fix out-of-bounds access in sysfs attribute read/write
CVE-2026-23238 romfs: check sb_set_blocksize() return value
CVE-2026-23237 platform/x86: classmate-laptop: Add missing NULL pointer checks

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23234

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