Linux: Use After Free
CVE-2026-23234 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 0fb58aff0dafd6837cc91f4154f3ed6e020358fa, 2f67ff1e15a8a4d0e4ffc6564ab20d03d7398fe9, 505e1c0530db6152cab3feef8e3e4da3d3e358c9 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 0fb58aff0dafd6837cc91f4154f3ed6e020358fa or 2f67ff1e15a8a4d0e4ffc6564ab20d03d7398fe9 or 505e1c0530db6152cab3feef8e3e4da3d3e358c9 or acc2c97fc0005846e5cf11b5ba3189fef130c9b3, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.251 or 5.15.201 or 6.1.164 or 6.6.127, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e234088758fca3a669ebb1a02d8bf7bf60f0e4ff up to, but not including, 0fb58aff0dafd6837cc91f4154f3ed6e020358fa; e234088758fca3a669ebb1a02d8bf7bf60f0e4ff up to, but not including, 2f67ff1e15a8a4d0e4ffc6564ab20d03d7398fe9; e234088758fca3a669ebb1a02d8bf7bf60f0e4ff up to, but not including, 505e1c0530db6152cab3feef8e3e4da3d3e358c9; e234088758fca3a669ebb1a02d8bf7bf60f0e4ff up to, but not including, acc2c97fc0005846e5cf11b5ba3189fef130c9b3; e234088758fca3a669ebb1a02d8bf7bf60f0e4ff up to, but not including, cf4a9e1bc8129eb63fda5f8bdcd8d87f0bd76f42; e234088758fca3a669ebb1a02d8bf7bf60f0e4ff up to, but not including, 995030be4ce6338c6ff814583c14166446a64008; e234088758fca3a669ebb1a02d8bf7bf60f0e4ff up to, but not including, a42f99be8a16b32a0bb91bb6dda212a6ad61be5d; e234088758fca3a669ebb1a02d8bf7bf60f0e4ff up to, but not including, ce2739e482bce8d2c014d76c4531c877f382aa54; and 1 more ranges | 0fb58aff0dafd6837cc91f4154f3ed6e020358fa, 2f67ff1e15a8a4d0e4ffc6564ab20d03d7398fe9, 505e1c0530db6152cab3feef8e3e4da3d3e358c9, acc2c97fc0005846e5cf11b5ba3189fef130c9b3, cf4a9e1bc8129eb63fda5f8bdcd8d87f0bd76f42, 995030be4ce6338c6ff814583c14166446a64008 |
| Linux | Linux Kernel | 3.13 up to, but not including, 5.10.251; 5.11 up to, but not including, 5.15.201; 5.16 up to, but not including, 6.1.164; 6.2 up to, but not including, 6.6.127; 6.7 up to, but not including, 6.12.74; 6.13 up to, but not including, 6.18.13; 6.19 up to, but not including, 6.19.3 | 5.10.251, 5.15.201, 6.1.164, 6.6.127, 6.12.74, 6.18.13 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
Official 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: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/0fb58aff0dafd6837cc91f4154f3ed6e020358fa
- git.kernel.org/stable/c/2f67ff1e15a8a4d0e4ffc6564ab20d03d7398fe9
- git.kernel.org/stable/c/505e1c0530db6152cab3feef8e3e4da3d3e358c9
- git.kernel.org/stable/c/995030be4ce6338c6ff814583c14166446a64008
- git.kernel.org/stable/c/a42f99be8a16b32a0bb91bb6dda212a6ad61be5d
- git.kernel.org/stable/c/acc2c97fc0005846e5cf11b5ba3189fef130c9b3
- git.kernel.org/stable/c/ce2739e482bce8d2c014d76c4531c877f382aa54
- git.kernel.org/stable/c/cf4a9e1bc8129eb63fda5f8bdcd8d87f0bd76f42
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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