CVE-2025-40190Public exploit

Filesystem corruption via EA inode refcount underflow

Published Nov 12, 2025 · Updated Aug 5, 2026

Integer underflow in the Linux ext4 filesystem allows attackers to corrupt files by supplying a crafted filesystem image. ext4_xattr_inode_update_ref() subtracts ref_change from an already nonpositive EA inode refcount and continues with the wrapped value, enabling orphan cleanup to free a still-referenced inode. An administrator or automounter must mount the image; stale references can disclose or corrupt file data, force the filesystem read-only, or panic the kernel.

CVSS severity7.8
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer underflow in the Linux ext4 filesystem allows attackers to corrupt files by supplying a crafted filesystem image. ext4_xattr_inode_update_ref() subtracts ref_change from an already nonpositive EA inode refcount and continues with the wrapped value, enabling orphan cleanup to free a still-referenced inode. An administrator or automounter must mount the image; stale references can disclose or corrupt file data, force the filesystem read-only, or panic the kernel.

The record

CVE
CVE-2025-40190
Published
Nov 12, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 12, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <5.10.246
  2. Affected versionversion=0 <5.15.195
  3. Affected versionversion=0 <5.4.301
  4. Affected versionversion=0 <6.1.157
  5. Affected versionversion=0 <6.12.54
  6. Affected versionversion=0 <6.17.4
  7. Affected versionversion=0 <6.6.113
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1cfb3e4ddbdc8e02e637b8852540bd4718bf4814
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3d6269028246f4484bfed403c947a114bb583631
  10. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <440b003f449a4ff2a00b08c8eab9ba5cd28f3943
  11. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <505e69f76ac497e788f4ea0267826ec7266b40c8
  12. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <57295e835408d8d425bef58da5253465db3d6888
  13. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6b879c4c6bbaab03c0ad2a983953bd1410bb165e
  14. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <79ea7f3e11effe1bd9e753172981d9029133a278
  15. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ea39e712c2f5ae148ee5515798ae03523673e002

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0 <5.10.246; version=0 <5.15.195; version=0 <5.4.301; version=0 <6.1.157; version=0 <6.12.54; version=0 <6.17.4; version=0 <6.6.113; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1cfb3e4ddbdc8e02e637b8852540bd4718bf4814; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3d6269028246f4484bfed403c947a114bb583631; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <440b003f449a4ff2a00b08c8eab9ba5cd28f3943; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <505e69f76ac497e788f4ea0267826ec7266b40c8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <57295e835408d8d425bef58da5253465db3d6888; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6b879c4c6bbaab03c0ad2a983953bd1410bb165e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <79ea7f3e11effe1bd9e753172981d9029133a278; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ea39e712c2f5ae148ee5515798ae03523673e002

Published CVSS scores

7.8Linux kernel CVE teamCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1499Endpoint Denial of Service
T1204.002Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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