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

> A race condition in the Linux kernel f2fs filesystem can cause inconsistent inode marking, leading to filesystem check errors and potential data integrity issues.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jul 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-53368, DEBIAN-CVE-2026-53368, GHSA-7cj6-gq26-374h, ROOT-OS-DEBIAN-11-CVE-2026-53368, ROOT-OS-DEBIAN-12-CVE-2026-53368, ROOT-OS-DEBIAN-13-CVE-2026-53368, ROOT-OS-UBUNTU-2204-CVE-2026-53368, UBUNTU-CVE-2026-53368

## What is CVE-2026-53368?

CVE-2026-53368 is a high-severity vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

## Which versions are affected by CVE-2026-53368?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53368?

Apply the vendor's patch.

## Is CVE-2026-53368 being exploited?

There is no known exploitation of CVE-2026-53368 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53368 and fix it if it is affected.

What it is: CVE-2026-53368 is a high-severity vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-53368 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53368/ (Markdown: https://insights.sbomify.com/CVE-2026-53368/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53368
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53368
- OSV: https://osv.dev/vulnerability/CVE-2026-53368

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53368/
Summaries are generated and may contain mistakes; the official description above is the record.