Cloudanix VulnDB

CVE-2026-80806

None

CVSS

—

EPSS

0.2%

Published

Sep 4, 2026

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A Linux file-system bug can let some encrypted files be stored without protection when a performance feature is turned on, risking exposure of sensitive data.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Moderate
Impact
Data Exposure
Component
OS kernel
Class
Other
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

The ext4 inode initialization sequence sets S_DAX on new encrypted regular files before EXT4_INODE_ENCRYPT is applied, allowing direct-access writes to bypass the encryption layer when the filesystem is mounted with dax=always.

Why it matters to the business

Encrypted data on ext4 volumes can be written in plaintext on disk, exposing sensitive information and potentially violating compliance or data-protection requirements in environments that rely on DAX for performance.

How an attack unfolds

An attacker with the ability to create files on a DAX-enabled ext4 filesystem mounts the volume with dax=always, creates a new encrypted regular file, and writes data to it; because S_DAX is set before encryption flags, the data is stored unencrypted.

How to fix it

Upgrade to a kernel containing the fix that moves EXT4_INODE_ENCRYPT initialization before the initial ext4_set_inode_flags call and prevents MAY_INLINE_DATA on encrypted inodes; rebuild and reboot affected systems.

How to confirm the fix worked

Confirm the running kernel contains the commit that sets EXT4_INODE_ENCRYPT earlier in __ext4_new_inode; reproduce by creating an encrypted file on a dax=always mount and verifying S_DAX is never set via statx or inode flags inspection.

Typical attack path

  1. Mount ext4 filesystem with the dax=always option
  2. Create a new encrypted regular file via standard userspace APIs
  3. Write data through the file descriptor
  4. Observe that the on-disk blocks contain plaintext rather than ciphertext

How to detect it

Search system logs and audit trails for ext4 mounts using dax=always combined with fscrypt-enabled directories; examine inode flags on newly created encrypted files for unexpected S_DAX presence.

What your security team should do

  • Apply the corrected kernel immediately on any system using ext4 with dax=always and encryption
  • Audit ext4 mount options and disable dax=always on encrypted volumes until patched
  • Monitor kernel changelogs for backported fixes in distribution kernels

The record

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.

Affected packages

Ecosystem Package Introduced Fixed