PT-2025-46747 · Ext4+2 · Ext4+2
Published
2025-09-20
·
Updated
2026-04-20
·
CVE-2025-40190
CVSS v2.0
6.8
Medium
| Vector | AV:L/AC:L/Au:S/C:C/I:C/A:C |
Name of the Vulnerable Software and Affected Versions
Linux kernel (affected versions not specified)
Description
The Linux kernel contains a flaw within the ext4 filesystem related to extended attribute (xattr) handling. Specifically, a race condition can occur during xattr updates, leading to an EA inode refcount underflow. This happens when
ext4 xattr inode update ref() reads a refcount that is already zero or negative and then attempts to decrement it. This can result in errors such as "EXT4-fs error: EA inode ref underflow" and "EXT4-fs warning: ea inode dec ref err=-117". The issue is addressed by preventing the refcount from underflowing and treating non-positive refcounts as on-disk corruption, failing the operation with -EFSCORRUPTED. The vulnerable code path was discovered by syzkaller.Recommendations
At the moment, there is no information about a newer version that contains a fix for this vulnerability.
Exploit
Integer Underflow
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Weakness Enumeration
Related Identifiers
Affected Products
Debian
Linux Kernel
Ext4