CVE-2025-37931

Filesystem corruption via misaligned subpage bitmap advance

Published May 20, 2025 · Updated Aug 5, 2026

Filesystem corruption in Linux and Siemens SIMATIC CN 4100 before 5.0 allows local users to corrupt btrfs volumes through file writes. In submit_eb_subpage, a clean extent-buffer range advances bit_start by one sector rather than sectors_per_node, misaligning radix-tree lookups and skipping dirty metadata writeback. The flaw requires a mounted btrfs filesystem with nodesize below PAGE_SIZE and can leave the volume corrupt, read-only, or unmountable.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Filesystem corruption in Linux and Siemens SIMATIC CN 4100 before 5.0 allows local users to corrupt btrfs volumes through file writes. In submit_eb_subpage, a clean extent-buffer range advances bit_start by one sector rather than sectors_per_node, misaligning radix-tree lookups and skipping dirty metadata writeback. The flaw requires a mounted btrfs filesystem with nodesize below PAGE_SIZE and can leave the volume corrupt, read-only, or unmountable.

The record

CVE
CVE-2025-37931
Published
May 20, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-20, T1485
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 20, 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=5.13
  2. Affected versionversion=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <396f4002710030ea1cfd4c789ebaf0a6969ab34f
  3. Affected versionversion=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <5111b148360f50cac9abbae8fca44cc0ac4bf9bf
  4. Affected versionversion=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <977849e8acd2466ac3cb49e04a3ecc73837f6b90
  5. Affected versionversion=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <b80db09b614cb7edec5bada1bc7c7b0eb3b453ea
  6. Affected versionversion=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <e08e49d986f82c30f42ad0ed43ebbede1e1e3739

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.13; version=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <396f4002710030ea1cfd4c789ebaf0a6969ab34f; version=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <5111b148360f50cac9abbae8fca44cc0ac4bf9bf; version=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <977849e8acd2466ac3cb49e04a3ecc73837f6b90; version=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <b80db09b614cb7edec5bada1bc7c7b0eb3b453ea; version=c4aec299fa8f73f0fd10bc556f936f0da50e3e83 <e08e49d986f82c30f42ad0ed43ebbede1e1e3739
Siemens · SIMATIC CN 4100version=0 <V5.0

Published CVSS scores

5.5Siemens ProductCERTCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1485Data Destruction

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo