CVE-2024-36904

Local denial of service via TCP refcount race

Published May 30, 2024 · Updated Aug 5, 2026

Use-after-free in the Linux TCP stack allows local users to crash an affected system by racing TCP port reuse during connect(). The tcp_twsk_unique() path increments a zero reference count after inet_twsk_hashdance() exposes a TIME-WAIT socket, then a later sock_put() underflows the count and frees live memory. A local low-privileged user must create competing TCP connections; the bounded documented consequence is kernel availability loss.

CVSS severity5.5
Medium
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux TCP stack allows local users to crash an affected system by racing TCP port reuse during connect(). The tcp_twsk_unique() path increments a zero reference count after inet_twsk_hashdance() exposes a TIME-WAIT socket, then a later sock_put() underflows the count and frees live memory. A local low-privileged user must create competing TCP connections; the bounded documented consequence is kernel availability loss.

The record

CVE
CVE-2024-36904
Published
May 30, 2024
Updated
Aug 5, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 30, 2024CVE 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=V3.1.0 <V3.1.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
The Linux Kernel Organization · Linuxversion=4.16; version=ec94c2696f0bcd5ae92a553244e4ac30d2171a2d <13ed7cdf079686ccd3618335205700c03f6fb446; version=ec94c2696f0bcd5ae92a553244e4ac30d2171a2d <1796ca9c6f5bd50554214053af5f47d112818ee3; version=ec94c2696f0bcd5ae92a553244e4ac30d2171a2d <1d9cf07810c30ef7948879567d10fd1f01121d34; version=ec94c2696f0bcd5ae92a553244e4ac30d2171a2d <27b0284d8be182a81feb65581ab6a724dfd596e8; version=ec94c2696f0bcd5ae92a553244e4ac30d2171a2d <517e32ea0a8c72202d0d8aa8df50a7cd3d6fdefc; version=ec94c2696f0bcd5ae92a553244e4ac30d2171a2d <6e48faad92be13166184d21506e4e54c79c13adc; version=ec94c2696f0bcd5ae92a553244e4ac30d2171a2d <84546cc1aeeb4df3e444b18a4293c9823f974be9; version=ec94c2696f0bcd5ae92a553244e4ac30d2171a2d <f2db7230f73a80dbb179deab78f88a7947f0ab7e
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 <V3.1
Siemens · RUGGEDCOM RST2428Pversion=0 <V3.1
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5

Published CVSS scores

5.5Siemens ProductCERTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.8CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 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-416Use After Free
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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