CVE-2021-3541

mediumpriority · track · 27EPSS 0.021 · 81 %ileDEEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

2.07% (81st) EPSS

CVSS 4 · medium

Is it mine?

64 products

Check your exposure

Who says so?

7 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-22

A flaw was found in libxml2. Exponential entity expansion attack its possible bypassing all existing protection mechanisms and leading to denial of service.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

FixedSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)siemens_psirt
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
FixedSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)siemens_psirt
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
FixedSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)siemens_psirt
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
FixedSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)siemens_psirt
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
FixedSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)siemens_psirt
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
Fixedruby4.0-rubygem-nokogiri-0:1.18.9-1.4.aarch64 as component of openSUSE Tumbleweedsuse_csaf
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Fixedruby4.0-rubygem-nokogiri-0:1.18.9-1.4.ppc64le as component of openSUSE Tumbleweedsuse_csaf
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Fixedruby4.0-rubygem-nokogiri-0:1.18.9-1.4.s390x as component of openSUSE Tumbleweedsuse_csaf
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Fixedruby4.0-rubygem-nokogiri-0:1.18.9-1.4.x86_64 as component of openSUSE Tumbleweedsuse_csaf
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
FixedAPM Edgecisa_csaf_ot
Hitachi Energy recommends users update to Transformer APM Edge v4.0. This version updates the software components to remediate this vulnerability.
FixedSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)cisa_csaf_ot
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
FixedSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)cisa_csaf_ot
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
FixedSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)cisa_csaf_ot
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
FixedSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)cisa_csaf_ot
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
FixedSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)cisa_csaf_ot
Update to V3.1.5 or later version
https://support.industry.siemens.com/cs/ww/en/view/109478459/
MitigationAPM Edgecisa_csaf_ot
Do not directly connect to the Internet.
MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)cisa_csaf_ot
Only build and run applications from trusted sources.
MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)cisa_csaf_ot
Only build and run applications from trusted sources.
MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)cisa_csaf_ot
Only build and run applications from trusted sources.
MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)cisa_csaf_ot
Only build and run applications from trusted sources.
MitigationSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)cisa_csaf_ot
Only build and run applications from trusted sources.

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4–7.5

v2.04mediumAV:N/AC:L/Au:S/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 8 · impact 2.9

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 3.6

v3.06.5mediumCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hsecondary · CISA US

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:Csecondary · Siemens ProductCERT DE

v3.16mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hsecondary · SUSE Product Security

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:Csecondary · CISA US

v3.17.5highAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-776USprimaryCWE-20USCWE-776USCWE-776US

affected products (64)

Products and version ranges known to be affected.

IBM InfoSphere Information Serverall versionscert_bundDEcpe:/a:ibm:infosphere_information_server:-
IBM QRadar SIEM 7.3all versionscert_bundDEcpe:/a:ibm:qradar_siem:7.3
IBM QRadar SIEM 7.4all versionscert_bundDEcpe:/a:ibm:qradar_siem:7.4
IBM QRadar SIEM 7.5.0all versionscert_bundDEcpe:/a:ibm:qradar_siem:7.5.0
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)all versionscisa_csaf_otUS
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)all versionscisa_csaf_otUS
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)all versionscisa_csaf_otUS
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)all versionscisa_csaf_otUS
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)all versionscisa_csaf_otUS
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)≤ vers:intdot/>=3.1.0|<3.1.5cisa_csaf_otUS
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)≤ vers:intdot/>=3.1.0|<3.1.5cisa_csaf_otUS
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)≤ vers:intdot/>=3.1.0|<3.1.5cisa_csaf_otUS
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)≤ vers:intdot/>=3.1.0|<3.1.5cisa_csaf_otUS
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)≤ vers:intdot/>=3.1.0|<3.1.5cisa_csaf_otUS
n/a libxml2≤ 2.9.11enisa_euvdEU
Canonical Ltd. Ubuntu≤ 16.04 ESMfstec_bduRU
Canonical Ltd. Ubuntu≤ 18.04 LTSfstec_bduRU
Canonical Ltd. Ubuntu≤ 14.04 ESMfstec_bduRU
Canonical Ltd. Ubuntu≤ 20.04 LTSfstec_bduRU
Canonical Ltd. Ubuntu≤ 20.10fstec_bduRU

showing 20 of 64

advisories (7)

Vendor and ecosystem advisories describing this.

SSA-398330SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.52023-12-12csaf · siemens_psirtDE
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version >= V3.1.0 and < V3.1.5 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). These GNU/Linux vulnerabilities have been externally identified. Siemens has released new versions for the affected products and recommends to update to the latest versions. SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5 are no longer maintained and there won't be any update to the CVE list anymore. Please update to the latest version. Note: This SSA advises vulnerabilities for firmware version V3.1 only; for versions < V3.1 refer to Siemens Security Bulletin SSB-439005 (https://cert-portal.siemens.com/productcert/html/ssb-439005.html).
WID-SEC-W-2022-1051libxml2: Schwachstelle ermöglicht Denial of ServiceDeutsch2021-06-09csaf · cert_bundDE
Ein entfernter, authentisierter Angreifer kann eine Schwachstelle in libxml2 ausnutzen, um einen Denial of Service Angriff durchzuführen.
WID-SEC-W-2023-1614Tenable Security Nessus Network Monitor: Mehrere SchwachstellenDeutsch2023-06-29csaf · cert_bundDE
Ein entfernter, anonymer, authentisierter oder lokaler Angreifer kann mehrere Schwachstellen in Tenable Security Nessus Network Monitor ausnutzen, um beliebigen Code auszuführen, vertrauliche Informationen offenzulegen, einen Denial-of-Service-Zustand auszulösen und Daten zu manipulieren.
WID-SEC-W-2025-0227IBM QRadar SIEM: Mehrere SchwachstellenDeutsch2021-11-30csaf · cert_bundDE
Ein entfernter, authentisierter Angreifer kann mehrere Schwachstellen in IBM QRadar SIEM ausnutzen, um seine Privilegien zu erweitern, Administratorrechte zu erlangen, beliebigen Programmcode auszuführen, Informationen offenzulegen, Dateien zu manipulieren oder Sicherheitsvorkehrungen zu umgehen.
openSUSE-SU-2026:10356-1ruby4.0-rubygem-nokogiri-1.18.9-1.4 on GA media2026-03-13csaf · suse_csafDE
ruby4.0-rubygem-nokogiri-1.18.9-1.4 on GA media
ICSA-21-336-06Hitachi Energy APM Edge2021-12-02icsa · cisa_csaf_otUS
Successful exploitation of this vulnerability could cause the product to become inaccessible.
ICSA-23-348-10Siemens SIMATIC S7-15002023-12-12icsa · cisa_csaf_otUS
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version >= V3.1.0 and < V3.1.5 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). These GNU/Linux vulnerabilities have been externally identified. Siemens has released new versions for the affected products and recommends to update to the latest versions. Note: This SSA advises vulnerabilities for firmware version V3.1 only; for versions < V3.1 refer to Siemens Security Bulletin SSB-439005 ( https://cert-portal.siemens.com/productcert/html/ssb-439005.html).

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund cisa_csaf_ot siemens_psirt suse_csaf NVD CVE.org MITRE

published 2021-07-09modified 2026-10-14

related (129)

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+124 more

references (48)

External citations — patches, advisories, analysis.

scry

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