CVE-2025-40196

Kernel panic via quota workqueue mismatch

Published Nov 12, 2025 · Updated Sep 8, 2026

Denial of service in Linux kernel quota writeback allows local users to panic affected systems by triggering an F2FS sync. dquot_writeback_dquots flushes quota_release_work from a reclaim-capable writeback path even though that work uses events_unbound without WQ_MEM_RECLAIM. The panic requires F2FS balance during synchronous writeback and panic_on_warn to be enabled, so the bounded consequence is a system crash.

CVSS severity5.5
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

Denial of service in Linux kernel quota writeback allows local users to panic affected systems by triggering an F2FS sync. dquot_writeback_dquots flushes quota_release_work from a reclaim-capable writeback path even though that work uses events_unbound without WQ_MEM_RECLAIM. The panic requires F2FS balance during synchronous writeback and panic_on_warn to be enabled, so the bounded consequence is a system crash.

The record

CVE
CVE-2025-40196
Published
Nov 12, 2025
Updated
Sep 8, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-20, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 12, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 8, 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=V3.1.6 <*

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.6 <*
The Linux Kernel Organization · Linuxversion=3e6ff207cd5bd924ad94cd1a7c633bcdac0ba1cb <8df2eedd371a1c24ecc4283581299d7737dfcd06; version=5.10.231 <5.11; version=5.15.174 <5.16; version=5.4.287 <5.5; version=6.1.120 <6.1.178; version=6.12.4 <6.12.54; version=6.13; version=6.6.64 <6.6.114; version=6f3821acd7c3143145999248087de5fb4b48cf26; version=8ea87e34792258825d290f4dc5216276e91cb224 <f12039df1515d5daf7d92e586ece5cefeb39561b; version=a5abba5e0e586e258ded3e798fe5f69c66fec198; version=ab6cfcf8ed2c7496f55d020b65b1d8cd55d9a2cb; version=ac6f420291b3fee1113f21d612fa88b628afab5b <72b7ceca857f38a8ca7c5629feffc63769638974; version=ac6f420291b3fee1113f21d612fa88b628afab5b <8a09a62f0c8c6123c2f1864ed6d5f9eb144afaf0; version=bcacb52a985f1b6d280f698a470b873dfe52728a <f846eacde280ecc3daedfe001580e3033565179e
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.6 <*
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.6 <*

Published CVSS scores

0.0Siemens ProductCERTCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:N
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 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
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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