CVE-2025-40190
ext4: guard against EA inode refcount underflow in xattr update
Description
In the Linux kernel, the following vulnerability has been resolved: ext4: guard against EA inode refcount underflow in xattr update syzkaller found a path where ext4_xattr_inode_update_ref() reads an EA inode refcount that is already <= 0 and then applies ref_change (often -1). That lets the refcount underflow and we proceed with a bogus value, triggering errors like: EXT4-fs error: EA inode <n> ref underflow: ref_count=-1 ref_change=-1 EXT4-fs warning: ea_inode dec ref err=-117 Make the invariant explicit: if the current refcount is non-positive, treat this as on-disk corruption, emit ext4_error_inode(), and fail the operation with -EFSCORRUPTED instead of updating the refcount. Delete the WARN_ONCE() as negative refcounts are now impossible; keep error reporting in ext4_error_inode(). This prevents the underflow and the follow-on orphan/cleanup churn.
INFO
Published Date :
Nov. 12, 2025, 10:15 p.m.
Last Modified :
Nov. 12, 2025, 10:15 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2025-40190
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Apply kernel patches for ext4 refcount underflow.
- Ensure refcounts remain positive.
- Handle non-positive refcounts as corruption.
- Remove redundant refcount warnings.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-40190.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-40190 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-40190
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-40190 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-40190 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Nov. 12, 2025
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: ext4: guard against EA inode refcount underflow in xattr update syzkaller found a path where ext4_xattr_inode_update_ref() reads an EA inode refcount that is already <= 0 and then applies ref_change (often -1). That lets the refcount underflow and we proceed with a bogus value, triggering errors like: EXT4-fs error: EA inode <n> ref underflow: ref_count=-1 ref_change=-1 EXT4-fs warning: ea_inode dec ref err=-117 Make the invariant explicit: if the current refcount is non-positive, treat this as on-disk corruption, emit ext4_error_inode(), and fail the operation with -EFSCORRUPTED instead of updating the refcount. Delete the WARN_ONCE() as negative refcounts are now impossible; keep error reporting in ext4_error_inode(). This prevents the underflow and the follow-on orphan/cleanup churn. Added Reference https://git.kernel.org/stable/c/1cfb3e4ddbdc8e02e637b8852540bd4718bf4814 Added Reference https://git.kernel.org/stable/c/3d6269028246f4484bfed403c947a114bb583631 Added Reference https://git.kernel.org/stable/c/440b003f449a4ff2a00b08c8eab9ba5cd28f3943 Added Reference https://git.kernel.org/stable/c/505e69f76ac497e788f4ea0267826ec7266b40c8 Added Reference https://git.kernel.org/stable/c/57295e835408d8d425bef58da5253465db3d6888 Added Reference https://git.kernel.org/stable/c/6b879c4c6bbaab03c0ad2a983953bd1410bb165e Added Reference https://git.kernel.org/stable/c/79ea7f3e11effe1bd9e753172981d9029133a278 Added Reference https://git.kernel.org/stable/c/ea39e712c2f5ae148ee5515798ae03523673e002