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Full vulnerability report · 2022
CVE-2021-45117High confidence

The OPC autogenerated ANSI C stack stubs (in the NodeSets) do not handle all error cases

Unknown · Unknown

Official source article: Siemens SSA-285795 ↗. Check the applicable product and release in the original source.

6.5MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 9 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 4 Aug 2024

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • EPSS is 1.42% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 9 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
SSA-285795 · CSAF 2.0 · revision 5 · interimSiemens ProductCERTSSA-285795: Denial of Service in OPC-UA in Industrial Products
9 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • SIMATIC HMI Comfort Outdoor Panels (incl. SIPLUS variants)
  • SIMATIC HMI Comfort Panels (incl. SIPLUS variants)
  • SIMATIC HMI KTP Mobile Panels KTP400F, KTP700, KTP700F, KTP900 and KTP900F
  • SIMATIC NET PC Software V14
  • SIMATIC NET PC Software V15
  • SIMATIC NET PC Software V16
  • SIMATIC NET PC Software V17
  • SITOP Manager
  • TeleControl Server Basic V3
Summary
The OPC UA ANSIC Stack (also called Legacy C-Stack) was reported to crash when an unexpected OPC UA Response message status code was accessed via the synchronous Client API. The vulnerability was found in generated code of the OPC Foundation C-Stack. An unexpected status code in response message will dereference Null pointer leading to crash, ping of death (PoD). This affects a client, but it might also affect a server when it uses OpcUa_ClientApi_RegisterServer (e.g. register at LDS). A specially crafted UA server, or Man in the Middle attacker, can cause the OPC UA application to crash by sending uncertain status code in response message.
Remediation
Update to V1.2.4 or later version
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-31899

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 9 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

The OPC autogenerated ANSI C stack stubs (in the NodeSets) do not handle all error cases. This can lead to a NULL pointer dereference.

What

The OPC autogenerated ANSI C stack stubs (in the NodeSets) do not handle all error cases. This can lead to a NULL pointer dereference.

Why

The product dereferences a pointer that it expects to be valid but is NULL.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

The OPC autogenerated ANSI C stack stubs (in the NodeSets) do not handle all error cases. This can lead to a NULL pointer dereference.

Why

The product dereferences a pointer that it expects to be valid but is NULL.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → NULL Pointer Dereference → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-476 ↗

CWE-476: NULL Pointer Dereference. The product dereferences a pointer that it expects to be valid but is NULL.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-476Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2023-2603Siemens SICAM: Mehrere Schwachstellen

Ein entfernter, anonymer oder lokaler Angreifer kann mehrere Schwachstellen in Siemens SICAM ausnutzen, um beliebigen Code auszuführen, Sicherheitsmaßnahmen zu umgehen, vertrauliche Informationen offenzulegen, einen Denial-of-Service-Zustand auszulösen, seine Privilegien zu erweitern und Daten zu manipulieren.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20220323Security Bulletin 23 Mar 2022

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 23 Mar 2022, published on 23 March 2022. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-435Multiples vulnérabilités dans les produits Siemens

36385.html Bulletin de sécurité Siemens ssa-787292 du 10 mai 2022 https://cert-portal.siemens.com/productcert/html/ssa-787292.html Bulletin de sécurité Siemens ssa-789162 du 10 mai 2022 https://cert-portal.siemens.com/productcert/html/ssa-789162.html Référence CVE CVE-2021-22901 https://www.cve.org/CVERecord?id=CVE-2021-22901 Référence CVE CVE-2021-22924 https://www.cve.org/CVERecord?id=CVE-2021-22924 Référence CVE CVE-2021-31340 https://www.cve.org/CVERecord?id=CVE-2021-31340 Référence CVE CVE-2021-40142 https://www.cve.org/CVERecord?id=CVE-2021-40142 Référence CVE CVE-2021-41545 https://www.cve.org/CVERecord?id=CVE-2021-41545 Référence CVE CVE-2021-45117 https://www.cve.org/CVERecord?id=CVE-2021-45117 Référence CVE CVE-2022-24039 https://www.cve.org/CVERecord?id=CVE-2022-24039 Référence CVE CVE-2022-24040 https://www.cve.org/CVERecord?id=CVE-2022-24040 Référence CVE CVE-2022-24041 https://www.cve.org/CVERecord?id=CVE-2022-24041 Référence CVE CVE-2022-24042 https://www.cve.org/CVERecord?id=CVE-2022-24042 Référence CVE CVE-2022-24043 https://www.cve.org/CVERecord?id=CVE-2022-24043 Référence CVE CVE-2022-24044 https://www.cve.org/CVERecord?id=CVE-2022-24044 Référence CVE CVE-2022-24045 https://www.cve.org/CVERecord?id=CVE-2022-24045 Référence CVE CVE-2022-24287 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-018979OPC Foundation の ua-nodeset 他複数ベンダの製品における NULL ポインタデリファレンスに関する脆弱性

OPC Foundation の ua-nodeset 他複数ベンダの製品には、NULL ポインタデリファレンスに関する脆弱性が存在します。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
Fixed
Update to V1.2.4 or later version
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 21 Mar 2022 · Last source change 4 Aug 2024, 04:39 UTC · CWE-476 · NULL Pointer Dereference

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-31899
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    n/a · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    n/a · Fixed: Update to V1.2.4 or later version
    Siemens ProductCERT ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2021-31899↗Siemens ProductCERT security advisory · Siemens SSA-285795↗Patch or update reference↗Patch or update reference↗Public exploit reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-45117 · cve.blacktree.nl