CVE-2025-40200

Service interruption via unchecked negative inode size

Published Nov 12, 2025 · Updated May 11, 2026

Improper validation in Linux Squashfs allows local users to interrupt service by mounting a filesystem with a negative file size. The squashfs_read_inode() path accepts a signed 64-bit inode size without rejecting negative values, so overlayfs receives an invalid file length during ovl_copy_up_file. Reaching the path requires local access, a mounted malformed Squashfs image, and overlayfs copy-up; vendors disagree on whether low or high privileges are required.

CVSS severity4.4
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper validation in Linux Squashfs allows local users to interrupt service by mounting a filesystem with a negative file size. The squashfs_read_inode() path accepts a signed 64-bit inode size without rejecting negative values, so overlayfs receives an invalid file length during ovl_copy_up_file. Reaching the path requires local access, a mounted malformed Squashfs image, and overlayfs copy-up; vendors disagree on whether low or high privileges are required.

The record

CVE
CVE-2025-40200
Published
Nov 12, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Nov 12, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=2.6.29
  2. Affected versionversion=6545b246a2c815a8fcd07d58240effb6ec3481b1 <2871c74caa3f4f05b429e6bfefebac62dbf1b408
  3. Affected versionversion=6545b246a2c815a8fcd07d58240effb6ec3481b1 <54170057a5fadd24a37b70de41e61d39284d9bd7
  4. Affected versionversion=6545b246a2c815a8fcd07d58240effb6ec3481b1 <8118f66124895829443d09c207e654adcb2f9321
  5. Affected versionversion=6545b246a2c815a8fcd07d58240effb6ec3481b1 <875fb3f87ae0225b881319ba016a1a8c4ffd5812
  6. Affected versionversion=6545b246a2c815a8fcd07d58240effb6ec3481b1 <8c7aad76751816207fee556d44aa88a710824810
  7. Affected versionversion=6545b246a2c815a8fcd07d58240effb6ec3481b1 <9f1c14c1de1bdde395f6cc893efa4f80a2ae3b2b
  8. Affected versionversion=6545b246a2c815a8fcd07d58240effb6ec3481b1 <f271155ff31aca8ef82c61c8df23ca97e9a77dd4
  9. Affected versionversion=6545b246a2c815a8fcd07d58240effb6ec3481b1 <fbfc745db628de31f5c089147deeb87e95b89e66

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.29; version=6545b246a2c815a8fcd07d58240effb6ec3481b1 <2871c74caa3f4f05b429e6bfefebac62dbf1b408; version=6545b246a2c815a8fcd07d58240effb6ec3481b1 <54170057a5fadd24a37b70de41e61d39284d9bd7; version=6545b246a2c815a8fcd07d58240effb6ec3481b1 <8118f66124895829443d09c207e654adcb2f9321; version=6545b246a2c815a8fcd07d58240effb6ec3481b1 <875fb3f87ae0225b881319ba016a1a8c4ffd5812; version=6545b246a2c815a8fcd07d58240effb6ec3481b1 <8c7aad76751816207fee556d44aa88a710824810; version=6545b246a2c815a8fcd07d58240effb6ec3481b1 <9f1c14c1de1bdde395f6cc893efa4f80a2ae3b2b; version=6545b246a2c815a8fcd07d58240effb6ec3481b1 <f271155ff31aca8ef82c61c8df23ca97e9a77dd4; version=6545b246a2c815a8fcd07d58240effb6ec3481b1 <fbfc745db628de31f5c089147deeb87e95b89e66

Published CVSS scores

4.4OracleCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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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