CVE-2025-68809 ksmbd: vfs: fix race on m_flags in vfs_cache
A race condition in the Linux kernel's ksmbd module can cause inconsistent file deletion states, potentially leading to data loss or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-68809?
CVE-2025-68809 is a critical vulnerability in Linux, published on 13 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: vfs: fix race on m_flags in vfs_cache
ksmbd maintains delete-on-close and pending-delete state in ksmbd_inode->m_flags. In vfs_cache.c this field is accessed under inconsistent locking: some paths read and modify m_flags under ci->m_lock while others do so without taking the lock at all.
Examples:
- ksmbd_query_inode_status() and __ksmbd_inode_close() use ci->m_lock when checking or updating m_flags. - ksmbd_inode_pending_delete(), ksmbd_set_inode_pending_delete(), ksmbd_clear_inode_pending_delete() and ksmbd_fd_set_delete_on_close() used to read and modify m_flags without ci->m_lock.
This creates a potential data race on m_flags when multiple threads open, close and delete the same file concurrently. In the worst case delete-on-close and pending-delete bits can be lost or observed in an inconsistent state, leading to confusing delete semantics (files that stay on disk after delete-on-close, or files that disappear while still in use).
Fix it by:
- Making ksmbd_query_inode_status() look at m_flags under ci->m_lock after dropping inode_hash_lock. - Adding ci->m_lock protection to all helpers that read or modify m_flags (ksmbd_inode_pending_delete(), ksmbd_set_inode_pending_delete(), ksmbd_clear_inode_pending_delete(), ksmbd_fd_set_delete_on_close()). - Keeping the existing ci->m_lock protection in __ksmbd_inode_close(), and moving the actual unlink/xattr removal outside the lock.
This unifies the locking around m_flags and removes the data race while preserving the existing delete-on-close behaviour.
Which versions are affected by CVE-2025-68809?
How do I fix CVE-2025-68809?
Apply the vendor's patch.
Is CVE-2025-68809 being exploited?
There is no known exploitation of CVE-2025-68809 in the wild and no public exploit code.
Sources
Also known as AZL-74423, BELL-CVE-2025-68809, DEBIAN-CVE-2025-68809, GHSA-ffpf-rf35-3fhq, ROOT-OS-DEBIAN-12-CVE-2025-68809, ROOT-OS-DEBIAN-13-CVE-2025-68809 and 3 more.