Linux Kernel F2fs f2fs_need_dentry_mark node_write improper synchronization

Summaryinfo

A vulnerability classified as problematic has been found in Linux Kernel. Impacted is the function f2fs_need_dentry_mark of the component F2fs. The manipulation of the argument node_write leads to improper synchronization. This vulnerability is traded as CVE-2026-53368. An attack has to be approached locally. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Linux Kernel (version now known). This issue affects the function f2fs_need_dentry_mark of the component F2fs. The manipulation of the argument node_write with an unknown input leads to a improper synchronization vulnerability. Using CWE to declare the problem leads to CWE-662. The product utilizes multiple threads or processes to allow temporary access to a shared resource that can only be exclusive to one process at a time, but it does not properly synchronize these actions, which might cause simultaneous accesses of this resource by multiple threads or processes. Impacted is integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-53368 since 06/09/2026. The exploitation is known to be easy. Attacking locally is a requirement. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/19/2026).

Applying the patch bedb710b63ae1bd617e65d0a8cf6cea1200b3753 is able to eliminate this problem.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Discussion