# CVE-2026-23267: f2fs: fix IS_CHECKPOINTED flag inconsistency issue caused by concurrent atomic commit and checkpoint writes > A race condition in the Linux kernel F2FS filesystem can cause mount failures and denial of service during concurrent atomic writes and checkpoints. - **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 18 Mar 2026 - **Updated:** 11 May 2026 - **Also known as:** BELL-CVE-2026-23267, DEBIAN-CVE-2026-23267, GHSA-9m9w-6gjg-9m6r, ROOT-OS-DEBIAN-11-CVE-2026-23267, ROOT-OS-UBUNTU-2204-CVE-2026-23267, ROOT-OS-UBUNTU-2404-CVE-2026-23267, UBUNTU-CVE-2026-23267 ## What is CVE-2026-23267? CVE-2026-23267 is a medium-severity vulnerability in Linux kernel, published on 18 Mar 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 IS_CHECKPOINTED flag inconsistency issue caused by concurrent atomic commit and checkpoint writes During SPO tests, when mounting F2FS, an -EINVAL error was returned from f2fs_recover_inode_page. The issue occurred under the following scenario Thread A Thread B f2fs_ioc_commit_atomic_write - f2fs_do_sync_file // atomic = true - f2fs_fsync_node_pages : last_folio = inode folio : schedule before folio_lock(last_folio) f2fs_write_checkpoint - block_operations// writeback last_folio - schedule before f2fs_flush_nat_entries : set_fsync_mark(last_folio, 1) : set_dentry_mark(last_folio, 1) : folio_mark_dirty(last_folio) - __write_node_folio(last_folio) : f2fs_down_read(&sbi->node_write)//block - f2fs_flush_nat_entries : {struct nat_entry}->flag |= BIT(IS_CHECKPOINTED) - unblock_operations : f2fs_up_write(&sbi->node_write) f2fs_write_checkpoint//return : f2fs_do_write_node_page() f2fs_ioc_commit_atomic_write//return SPO Thread A calls f2fs_need_dentry_mark(sbi, ino), and the last_folio has already been written once. However, the {struct nat_entry}->flag did not have the IS_CHECKPOINTED set, causing set_dentry_mark(last_folio, 1) and write last_folio again after Thread B finishes f2fs_write_checkpoint. After SPO and reboot, it was detected that {struct node_info}->blk_addr was not NULL_ADDR because Thread B successfully write the checkpoint. This issue only occurs in atomic write scenarios. For regular file fsync operations, the folio must be dirty. If block_operations->f2fs_sync_node_pages successfully submit the folio write, this path will not be executed. Otherwise, the f2fs_write_checkpoint will need to wait for the folio write submission to complete, as sbi->nr_pages[F2FS_DIRTY_NODES] > 0. Therefore, the situation where f2fs_need_dentry_mark checks that the {struct nat_entry}->flag /wo the IS_CHECKPOINTED flag, but the folio write has already been submitted, will not occur. Therefore, for atomic file fsync, sbi->node_write should be acquired through __write_node_folio to ensure that the IS_CHECKPOINTED flag correctly indicates that the checkpoint write has been completed. ## Which versions are affected by CVE-2026-23267? It affects 1 product. Products: Linux kernel. ## How do I fix CVE-2026-23267? Apply the vendor's patch. ## Is CVE-2026-23267 being exploited? There is no known exploitation of CVE-2026-23267 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-2026-23267 and fix it if it is affected. What it is: CVE-2026-23267 is a medium-severity vulnerability in Linux kernel, published on 18 Mar 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-2026-23267 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-2026-23267/ (Markdown: https://insights.sbomify.com/CVE-2026-23267/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23267 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23267 - OSV: https://osv.dev/vulnerability/CVE-2026-23267 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-23267/ Summaries are generated and may contain mistakes; the official description above is the record.