# CVE-2026-53368: f2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage

CVE-2026-53368 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-53368, released July 20, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-53368
- Priority: High
- CVSS: 7.1 (Important)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 19, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-53368

## Description

In the Linux kernel, the following vulnerability has been resolved:  f2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage  f2fs_need_dentry_mark() reads nat_entry flags without mutual exclusion with the checkpoint path, which can result in an incorrect inode block marking state. The scenario is as follows:  create & write & fsync 'file A'                 write checkpoint - f2fs_do_sync_file // inline inode  - f2fs_write_inode // inode folio is dirty                                                 - f2fs_write_checkpoint                                                  - f2fs_flush_merged_writes                                                  - f2fs_sync_node_pages  - f2fs_fsync_node_pages // no dirty node  - f2fs_need_inode_block_update // return true  - f2fs_fsync_node_pages // inode dirtied   - f2fs_need_dentry_mark //return true                                                  - f2fs_flush_nat_entries                                                 - f2fs_write_checkpoint end   - __write_node_folio // inode with DENT_BIT_SHIFT set   SPO, "fsck --dry-run" find inode has already checkpointed but still   with DENT_BIT_SHIFT set  The state observed by f2fs_need_dentry_mark() can differ from the state observed in __write_node_folio() after acquiring sbi->node_write. The root cause is that the semantics of IS_CHECKPOINTED and HAS_FSYNCED_INODE are only guaranteed after the checkpoint write has fully completed.  This patch moves set_dentry_mark() into __write_node_folio() and protects it with the sbi->node_write lock.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-53368](https://patchblox.com/security/data/fix/linux/debian-cve-2026-53368.md) | Jul 20, 2026 |
| Linux | linux Debian 14 | 7.0.7-1 | [DEBIAN-CVE-2026-53368](https://patchblox.com/security/data/fix/linux/debian-cve-2026-53368.md) | Jul 20, 2026 |

---

Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.