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VulnerabilityPublished Updated

CVE-2025-40167: Linux kernel · ext4: detect invalid INLINE_DATA + EXTENTS flag combination

Source GCVE Database

0

Not known to be exploited · CVSS 7.8 High.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Nov 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

AI-suggested

A fix is available that detects and rejects inodes with the invalid INLINE_DATA and EXTENTS flag combination early in ext4_iget(). Users should apply the official Linux kernel updates that address this issue. Since no explicit patch links are provided here, consult the Linux kernel vendor advisories or mainline kernel updates for the fix. No additional mitigations are indicated by the vendor advisory.

Description

A vulnerability in the Linux kernel's ext4 filesystem was identified where an inode could have both INLINE_DATA and EXTENTS flags set simultaneously, an invalid state. This flaw leads to skipping extent tree validation, causing a kernel BUG_ON due to integer underflow when processing corrupted extents. The issue was reported by syzbot and affects ext4 filesystems mounted without a journal. The fix involves detecting and rejecting inodes with this invalid flag combination early during inode retrieval.

References

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