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NVD / CVE Program· CNA Linux

CVE-2025-40190: ext4: guard against EA inode refcount underflow in xattr update

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
  • Someone with local access to the system can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 1cfb3e4ddbdc8e02e637b8852540bd4718bf4814, 3d6269028246f4484bfed403c947a114bb583631, 440b003f449a4ff2a00b08c8eab9ba5cd28f3943; azl3 kernel 6.6.112.1-2 on Azure Linux 3.0 6.6.117.1-1.

Low priority for now. Upgrade to Linux Linux 1cfb3e4ddbdc8e02e637b8852540bd4718bf4814, 3d6269028246f4484bfed403c947a114bb583631, 440b003f449a4ff2a00b08c8eab9ba5cd28f3943; azl3 kernel 6.6.112.1-2 on Azure Linux 3.0 6.6.117.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Nov 12, 2025
Updated
Oct 19, 2026
EPSS
0.1% · 7th percentile
CWE
—

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before ea39e712c2f5ae148ee5515798ae03523673e002affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 1cfb3e4ddbdc8e02e637b8852540bd4718bf4814affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 505e69f76ac497e788f4ea0267826ec7266b40c8affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 3d6269028246f4484bfed403c947a114bb583631affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 79ea7f3e11effe1bd9e753172981d9029133a278affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 6b879c4c6bbaab03c0ad2a983953bd1410bb165eaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 440b003f449a4ff2a00b08c8eab9ba5cd28f3943affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 57295e835408d8d425bef58da5253465db3d6888affected · git
    • before 5.4.301affected · semver
    • before 5.10.246affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.158-16.1.158-1
Debian:13linuxbefore 6.12.57-16.12.57-1
Debian:14linuxbefore 6.17.6-16.17.6-1
openSUSE:Leap 16.0dtb-aarch64before 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-64kbbefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-azurebefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-defaultbefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-default-basebefore 6.12.0-160000.9.1.160000.2.66.12.0-160000.9.1.160000.2.6
openSUSE:Leap 16.0kernel-docsbefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-kvmsmallbefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-obs-buildbefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-obs-qabefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-rtbefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-sourcebefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-symsbefore 6.12.0-160000.9.16.12.0-160000.9.1
openSUSE:Leap 16.0kernel-zfcpdumpbefore 6.12.0-160000.9.16.12.0-160000.9.1
SUSE:Linux Enterprise Server 16.0kernel-azurebefore 6.12.0-160000.9.16.12.0-160000.9.1
SUSE:Linux Enterprise Server 16.0kernel-docsbefore 6.12.0-160000.9.16.12.0-160000.9.1
SUSE:Linux Enterprise Server 16.0kernel-kvmsmallbefore 6.12.0-160000.9.16.12.0-160000.9.1
SUSE:Linux Enterprise Server 16.0kernel-obs-qabefore 6.12.0-160000.9.16.12.0-160000.9.1
SUSE:Linux Enterprise Server 16.0kernel-symsbefore 6.12.0-160000.9.16.12.0-160000.9.1
SUSE:Linux Enterprise Server 16.0kernel-zfcpdumpbefore 6.12.0-160000.9.16.12.0-160000.9.1
SUSE:Linux Micro 6.2kernel-64kbbefore 6.12.0-160000.9.16.12.0-160000.9.1
SUSE:Linux Micro 6.2kernel-defaultbefore 6.12.0-160000.9.16.12.0-160000.9.1

+4

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2025-40188Nov 12, 2025 · pwm: berlin: Fix wrong register in suspend/resume
    0Monitor
  • ← EarlierCVE-2025-40189Nov 12, 2025 · net: usb: lan78xx: Fix lost EEPROM read timeout error(-ETIMEDOUT) in lan78xx_read_raw_eeprom
    0Monitor
  • Later →CVE-2025-40191Nov 12, 2025 · drm/amdkfd: Fix kfd process ref leaking when userptr unmapping
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux1cfb3e4ddbdc8e02e637b8852540bd4718bf4814Vendor (CNA)
Linux Linux3d6269028246f4484bfed403c947a114bb583631Vendor (CNA)
Linux Linux440b003f449a4ff2a00b08c8eab9ba5cd28f3943Vendor (CNA)
Linux Linux5.10.246Vendor (CNA)
Linux Linux5.15.195Vendor (CNA)
Linux Linux5.4.301Vendor (CNA)
Linux Linux505e69f76ac497e788f4ea0267826ec7266b40c8Vendor (CNA)
Linux Linux57295e835408d8d425bef58da5253465db3d6888Vendor (CNA)
Linux Linux6.1.157Vendor (CNA)
Linux Linux6.12.54Vendor (CNA)
Linux Linux6.17.4Vendor (CNA)
Linux Linux6.6.113Vendor (CNA)
Linux Linux6b879c4c6bbaab03c0ad2a983953bd1410bb165eVendor (CNA)
Linux Linux79ea7f3e11effe1bd9e753172981d9029133a278Vendor (CNA)
Linux Linuxea39e712c2f5ae148ee5515798ae03523673e002Vendor (CNA)
azl3 kernel 6.6.112.1-2 on Azure Linux 3.06.6.117.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.158-1 · Debian:12Package registry (OSV)
opensuse:dtb-aarch646.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-64kb6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-azure6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default-base6.12.0-160000.9.1.160000.2.6 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-docs6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-kvmsmall6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-build6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-qa6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-rt6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-source6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-syms6.12.0-160000.9.1 · openSUSE:Leap 16.0Package registry (OSV)
suse:kernel-64kb6.12.0-160000.9.1 · SUSE:Linux Micro 6.2Package registry (OSV)

+11

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records