CVE-2026-80806
Received Received - Intake

ext4 Filesystem DAX Encryption Bypass Vulnerability

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: kernel.org

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.

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-04
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-80806
EUVD
EUVD-2026-71241

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel allows encrypted files to be created without proper encryption enforcement when the filesystem is mounted with 'dax=always'. The issue occurs because the inode flags are set before encryption is applied, causing data to bypass encryption and leading to potential data exposure.

Detection Guidance

This vulnerability affects the Linux kernel's ext4 filesystem when handling encrypted files with DAX enabled. Detection requires checking kernel version and filesystem mount options. Use 'uname -r' to check kernel version and 'mount | grep dax=always' to see if any filesystems are mounted with DAX enabled. If using an affected kernel version with DAX on encrypted files, the system is vulnerable.

Impact Analysis

If you use Linux systems with ext4 filesystems mounted with 'dax=always' and create encrypted files, this vulnerability could allow unauthorized access to sensitive data. Attackers might read unencrypted data written to these files, violating confidentiality.

Compliance Impact

This vulnerability could lead to non-compliance with data protection regulations like GDPR or HIPAA by exposing sensitive data. Organizations using affected systems may face legal penalties, reputational damage, and loss of trust due to unauthorized data access.

Mitigation Strategies

Apply the kernel patch that fixes this issue. If patching is not immediately possible, disable DAX on encrypted filesystems by remounting without 'dax=always' or updating mount options. Avoid creating encrypted files on DAX-enabled filesystems until patched.

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