CVE-2025-40190
- Published: 2025-11-12T22:15:45.960
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 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.
Related CVE by CWE
No related CWE found.
Top CVE for Vendor
No vendor taxonomy on this entry.
Recently Exploited Similar Vulnerabilities
No recent KEV-listed items for this vendor/product.
How to fix CVE-2025-40190
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 […]
Exploit Difficulty: HARD
⏱️ Time to exploit: > 4 hours
🛠️ Required skills: Advanced security expertise
💰 Public exploits: Rare or not public
How to Fix:
- Check if you're running the affected product
- Update to the latest patched version
- If patching is not immediately possible: restrict network exposure, apply least-privilege access
- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)
- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations
Exploit Difficulty Assessment
Vulnerability Timeline
CVE details first published to NVD database
Added to this CVE tracking system
Detection Rules & IOCs
No specific detection rules generated for this vulnerability type.
No vendor/product data available.