CVE-2026-74308
Received Received - Intake

Kernel BUG in Linux Kernel ext4 Filesystem

Vulnerability report for CVE-2026-74308, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-15

Last updated on: 2026-08-17

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix kernel BUG in ext4_write_inline_data_end When the data=journal mount option is used, the ext4_journalled_write_end() function incorrectly calls ext4_write_inline_data_end() without checking if the EXT4_STATE_MAY_INLINE_DATA flag is still set on the inode. If a previous attempt to convert the inline data to an extent failed (e.g. due to ENOSPC), the EXT4_STATE_MAY_INLINE_DATA flag is cleared, but the EXT4_INODE_INLINE_DATA flag remains set. In this scenario, the next call to ext4_write_begin() will not prepare the inline data xattr for writing, but ext4_journalled_write_end() will incorrectly attempt to write to it, triggering a BUG_ON(pos + len > EXT4_I(inode)->i_inline_size) in ext4_write_inline_data() since i_inline_size was not expanded. Fix this by ensuring that ext4_journalled_write_end() only calls ext4_write_inline_data_end() if the EXT4_STATE_MAY_INLINE_DATA flag is set, mirroring the behavior of ext4_write_end() and ext4_da_write_end().

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Meta Information

Published
2026-08-15
Last Modified
2026-08-17
Generated
2026-09-04
AI Q&A
2026-08-15
EPSS Evaluated
2026-09-03
NVD
EUVD

Affected Vendors & Products

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

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel occurs when the ext4 filesystem uses the data=journal mount option. It involves a kernel bug where ext4_journalled_write_end() incorrectly calls ext4_write_inline_data_end() without verifying if the EXT4_STATE_MAY_INLINE_DATA flag is set. If a previous inline data conversion failed, this flag is cleared while EXT4_INLINE_DATA remains, leading to a BUG_ON trigger in ext4_write_inline_data() due to incorrect inline size handling.

Detection Guidance

This vulnerability is specific to the Linux kernel's ext4 filesystem with the data=journal mount option. Detection requires checking kernel logs for BUG_ON errors related to ext4_write_inline_data_end or examining mount options and filesystem state for affected systems.

Impact Analysis

This vulnerability can cause system crashes or kernel panics when writing to ext4 filesystems with data=journal enabled. It may lead to data corruption or loss if the filesystem becomes unstable. Users relying on inline data features could experience unexpected failures during file operations.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA as it is a kernel-level bug in the ext4 filesystem. It may indirectly impact compliance if it leads to data corruption or integrity issues, but no specific compliance impact is mentioned in the provided context.

Mitigation Strategies

Apply the Linux kernel patch that fixes this issue. If using data=journal mount option, consider temporarily switching to data=ordered or data=writeback until patched. Monitor kernel logs for related errors.

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