CVE-2024-36903

Kernel availability loss via IPv6 flag race

Published May 30, 2024 · Updated Sep 8, 2026

A race condition in Linux IPv6 packet construction allows attackers to cause kernel availability loss through uninitialized-value access. The __ip6_make_skb() path tests the socket HDRINCL state instead of FLOWI_FLAG_KNOWN_NH in flowi6_flags, permitting a concurrent state change to expose an uninitialized value. Reachability is deployment-dependent: NVD treats exploitation as local and low-privileged, while Siemens treats affected controllers as remotely reachable without authentication.

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

A race condition in Linux IPv6 packet construction allows attackers to cause kernel availability loss through uninitialized-value access. The __ip6_make_skb() path tests the socket HDRINCL state instead of FLOWI_FLAG_KNOWN_NH in flowi6_flags, permitting a concurrent state change to expose an uninitialized value. Reachability is deployment-dependent: NVD treats exploitation as local and low-privileged, while Siemens treats affected controllers as remotely reachable without authentication.

The record

CVE
CVE-2024-36903
Published
May 30, 2024
Updated
Sep 8, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-362, CWE-908, T1499.004
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. May 30, 2024CVE 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 vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.6 <*
The Linux Kernel Organization · Linuxversion=02ed5700f40445af02d1c97db25ffc2d04971d9f; version=0cf600ca1bdf1d52df977516ee6cee0cadb1f6b1; version=165370522cc48127da564a08584a7391e6341908; version=2c9cefc142c1dc2759e19a92d3b2b3715e985beb <a05c1ede50e9656f0752e523c7b54f3a3489e9a8; version=4.14.313 <4.15; version=4.19.281 <4.20; version=5.10.178 <5.10.248; version=5.15.107 <5.15.198; version=5.4.241 <5.5; version=605b056d63302ae84eb136e88d4df49124bd5e0d <59d74c843ebf46264c7903726cf6f2673a93b07a; version=6.1.24 <6.1.140; version=6.2.11 <6.3; version=6.3; version=d65ff2fe877c471aa6e79efa7bd8ff66e147c317 <40e5444a3ac315b60e94d82226b73cd82145d09e; version=ea30388baebcce37fd594d425a65037ca35e59e8 <2367bf254f3a27ecc6e229afd7a8b0a1395f7be3; version=ea30388baebcce37fd594d425a65037ca35e59e8 <4e13d3a9c25b7080f8a619f961e943fe08c2672c; version=ea30388baebcce37fd594d425a65037ca35e59e8 <68c8ba16ab712eb709c6bab80ff151079d11d97a; version=f394f690a30a5ec0413c62777a058eaf3d6e10d5
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

5.6Siemens ProductCERTCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
5.5NVDCVSS: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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization
CWE-908Use of Uninitialized Resource
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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