LiveActive security incident?Get immediate response
CVE Record

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

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.

UnknownCVSS not scoredNot KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-23234 is a Linux kernel F2FS filesystem bug. A race during writeback completion and unmount can cause use-after-free access to freed kernel filesystem state. The public record says it is fixed in upstream stable commits, but provides no CVSS score and no evidence of active exploitation.

Executive priority

Treat as a scheduled kernel maintenance item, higher priority where F2FS is used. There is no cited active exploitation or CVSS score, but kernel memory-safety bugs can affect platform stability and security boundaries.

Technical view

The flaw is in f2fs_write_end_io(). A syzbot-reported race involving loop-backed I/O completion and kill_f2fs_super()/f2fs_put_super() can free sbi before later writeback accounting accesses it. The fix moves checkpoint thread wakeup handling before folio_end_writeback() to avoid accessing freed state.

Likely exposure

Exposure is most relevant to Linux systems with F2FS enabled or mounted. The source lists Linux kernel versions and stable fix commits, but distro backport status is not included. Systems not using F2FS are less likely to encounter the vulnerable path.

Exploitation context

The public sources describe a race condition found by syzbot, not an in-the-wild attack. CISA KEV is false in the provided bundle. The record does not establish remote exploitability, privilege requirements, or practical exploitation reliability.

Researcher notes

Evidence is limited to the CVE record and kernel stable commits. The affected-version data appears broad and should be reconciled with exact upstream and distribution kernel trees. Avoid assuming exploitability beyond the documented use-after-free race.

Mitigation direction

  • Update to a kernel build containing the referenced upstream stable F2FS fix.
  • Prioritize systems that mount or allow F2FS filesystems.
  • Use distribution vendor advisories to confirm backported fixes.
  • If patching is delayed, check vendor guidance for supported mitigations.

Validation and detection

  • Inventory Linux kernel versions across affected fleets.
  • Identify hosts with F2FS support enabled or F2FS filesystems mounted.
  • Confirm the relevant stable fix commit is present or backported.
  • Monitor CVE and vendor records for severity or exploitation updates.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2026-23234 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
9Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxe234088758fca3a669ebb1a02d8bf7bf60f0e4ff, e234088758fca3a669ebb1a02d8bf7bf60f0e4ff, e234088758fca3a669ebb1a02d8bf7bf60f0e4ff, e234088758fca3a669ebb1a02d8bf7bf60f0e4ff, e234088758fca3a669ebb1a02d8bf7bf60f0e4ff, e234088758fca3a669ebb1a02d8bf7bf60f0e4ff, e234088758fca3a669ebb1a02d8bf7bf60f0e4ff, e234088758fca3a669ebb1a02d8bf7bf60f0e4ffunaffected
LinuxLinux3.13, 0, 5.10.251, 5.15.201, 6.1.164, 6.6.127, 6.12.74, 6.18.13, 6.19.3, 7.0affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.