CVE-2025-21846

Kernel crash via post-exit accounting write

Published Mar 12, 2025 · Updated Sep 8, 2026

NULL pointer dereference in Linux kernel process accounting allows local users to crash the system through a lookup-triggering acct(2) target. The final accounting write runs after the exiting task has called exit_fs(), so an internal lookup such as one for /sys/power/resume dereferences the absent current->fs pointer. Triggering the crash requires local access and CAP_SYS_PACCT; the reported consequence is a kernel service interruption, not data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux kernel process accounting allows local users to crash the system through a lookup-triggering acct(2) target. The final accounting write runs after the exiting task has called exit_fs(), so an internal lookup such as one for /sys/power/resume dereferences the absent current->fs pointer. Triggering the crash requires local access and CAP_SYS_PACCT; the reported consequence is a kernel service interruption, not data disclosure or modification.

The record

CVE
CVE-2025-21846
Published
Mar 12, 2025
Updated
Sep 8, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 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 <*
Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <56d5f3eba3f5de0efdd556de4ef381e109b973a9; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5a59ced8ffc71973d42c82484a719c8f6ac8f7f7; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5c928e14a2ccd99462f2351ead627b58075bb736; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5d5b936cfa4b0d5670ca7420ef165a074bc008eb; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5ee8da9bea70dda492d61f075658939af33d8410; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8acbf4a88c6a98c8ed00afd1a7d1abcca9b4735e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a8136afca090412a36429cb6c2543c714d9c0f84; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b03782ae707cc45e65242c7cddd8e28f1c22cde5; version=2.6.12
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

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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