CVE-2026-80806 ext4: don't enable DAX on new encrypted files
Attackers can bypass encryption on new ext4 files if DAX is enabled, allowing unauthorized access to plaintext data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80806?
CVE-2026-80806 is a vulnerability in Linux, published on 4 Sep 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:
ext4: don't enable DAX on new encrypted files
Currently, when a new encrypted regular file is created, the call to ext4_set_inode_flags(inode, init=true) in __ext4_new_inode() is made before EXT4_INODE_ENCRYPT is set. As a result, it can set S_DAX if the filesystem is mounted with "-o dax=always".
EXT4_INODE_ENCRYPT then actually gets set a bit later in __ext4_new_inode(), when it calls fscrypt_set_context() which calls ext4_set_context(). ext4_set_context() sets EXT4_INODE_ENCRYPT and calls ext4_set_inode_flags(inode, init=false) to set S_ENCRYPTED too.
This was intended to clear S_DAX as well. However, this was broken by commit 043546e46dc7 ("fs/ext4: Only change S_DAX on inode load"). This causes data written to the file to bypass encryption, also causing xfstests failures such as generic/548 (when "-o dax=always" is used).
Fix this by simplifying the flow by making __ext4_new_inode() set EXT4_INODE_ENCRYPT earlier. This makes it take effect in ext4_set_inode_flags(inode, init=true), making S_DAX never be set.
Similarly, make EXT4_STATE_MAY_INLINE_DATA never be set in the first place on new encrypted inodes. Then it doesn't need to be cleared.
As a result of these simplifications, ext4_set_context() no longer needs to change inode flags or state when 'handle != NULL'. Remove that too.
Which versions are affected by CVE-2026-80806?
How do I fix CVE-2026-80806?
Apply the vendor's patch.
Is CVE-2026-80806 being exploited?
There is no known exploitation of CVE-2026-80806 in the wild and no public exploit code.
Sources
Also known as AZL-99669, BELL-CVE-2026-80806, DEBIAN-CVE-2026-80806, GHSA-jqxc-3f8r-hc2f, UBUNTU-CVE-2026-80806.