CVE-2025-21864

System crash via retained TCP secpath reference

Published Mar 12, 2025 · Updated Sep 8, 2026

Resource-lifetime error in the Linux kernel allows local users to crash the system during network-namespace teardown with IPComp6 TCP traffic. Deferred freeing leaves an skb secpath attached after the TCP receive path drops its dst, retaining an unexpected xfrm_state reference past namespace deletion. Reachability requires privileges to create and delete network namespaces and send TCP traffic over IPComp6; the documented impact is availability only.

CVSS severity5.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource-lifetime error in the Linux kernel allows local users to crash the system during network-namespace teardown with IPComp6 TCP traffic. Deferred freeing leaves an skb secpath attached after the TCP receive path drops its dst, retaining an unexpected xfrm_state reference past namespace deletion. Reachability requires privileges to create and delete network namespaces and send TCP traffic over IPComp6; the documented impact is availability only.

The record

CVE
CVE-2025-21864
Published
Mar 12, 2025
Updated
Sep 8, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-476, T1499
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=V3.1.5 <*
  2. 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=V3.1.5 <*; version=V3.1.6 <*
The Linux Kernel Organization · Linuxversion=5.19; version=68822bdf76f10c3dc80609d4e2cdc1e847429086 <69cafd9413084cd5012cf5d7c7ec6f3d493726d9; version=68822bdf76f10c3dc80609d4e2cdc1e847429086 <87858bbf21da239ace300d61dd209907995c0491; version=68822bdf76f10c3dc80609d4e2cdc1e847429086 <9b6412e6979f6f9e0632075f8f008937b5cd4efd; version=68822bdf76f10c3dc80609d4e2cdc1e847429086 <cd34a07f744451e2ecf9005bb7d24d0b2fb83656; version=68822bdf76f10c3dc80609d4e2cdc1e847429086 <f1d5e6a5e468308af7759cf5276779d3155c5e98
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.5 <*; version=V3.1.6 <*
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*; version=V3.1.6 <*

Published CVSS scores

5.5CISA ADP VulnrichmentCVSS: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-476NULL Pointer Dereference
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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