CVE-2025-21694

Crash-dump hang via unrescheduled vmcore read loop

Published Feb 12, 2025 · Updated May 23, 2026

Improper locking in Linux kernel __read_vmcore allows local users to stall crash-dump collection during kdump processing. The second __read_vmcore loop lacks a guaranteed rescheduling point, which can starve RCU memory reclamation in a constrained kdump image. Local privileges and an active kdump operation are required; the bounded consequence is a stuck crash dump, not data exposure or modification.

CVSS severity4.1
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

Improper locking in Linux kernel __read_vmcore allows local users to stall crash-dump collection during kdump processing. The second __read_vmcore loop lacks a guaranteed rescheduling point, which can starve RCU memory reclamation in a constrained kdump image. Local privileges and an active kdump operation are required; the bounded consequence is a stuck crash dump, not data exposure or modification.

The record

CVE
CVE-2025-21694
Published
Feb 12, 2025
Updated
May 23, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-667, T1499.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Feb 12, 2025CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=V3.1.0 <V3.1.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 familyversion=0 <V3.2
Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
The Linux Kernel Organization · Linuxversion=4.19.317 <4.20; version=5.10.221 <5.10.234; version=5.15.162 <5.15.177; version=518fbd644dabb6aedbdd4939c6c9cc1bf651459f <a5a2ee8144c3897d37403a69118c3e3dc5713958; version=5.4.279 <5.4.290; version=5cbcb62dddf5346077feb82b7b0c9254222d3445 <80828540dad0757b6337c6561d49c81038f38d87; version=5cbcb62dddf5346077feb82b7b0c9254222d3445 <cbc5dde0a461240046e8a41c43d7c3b76d5db952; version=6.10; version=6.1.95 <6.1.127; version=6.6.35 <6.6.74; version=6.9.6 <6.10; version=70c1835e776c8447c1aca87ddb38cfe764fe756a <80da29deb88a3a907441fc35bb7bac309f31e713; version=7bdf1d550ddfcd9ab797087421f77b7aceddc8a7; version=803d5a33d5ffdc2d86dcc0cfa01655a330612cdb <84c4ed15626574c9ac6c1039ba9c137a77bcc7f2; version=a373ad833a6bfe4bc6cedcf7e56a99cc6fd9a193 <65c367bd9d4f43513c7f837df5753bea9561b836; version=e1b160a50c756e0efbea290b9bf5117cb80e8c4b <649b266606bc413407ce315f710c8ce8a88ee30a; version=e8780e8a0e25dc4c3927f611ec8970d26c0c7369
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SCALANCE XCM/XRM/XCH/XRH-300 familyversion=0 <V3.2
Siemens · RUGGEDCOM RST2428Pversion=0 <V3.2
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5

Published CVSS scores

5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/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
4.1Siemens ProductCERTCVSS:3.1/AV:L/AC:H/PR:H/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-667Improper Locking
T1499.004Application 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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