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Full vulnerability report · 2021
CVE-2021-25677High confidence

Siemens APOGEE PXC Compact (BACnet) — Use of Insufficiently Random Values

Siemens · APOGEE PXC Compact (BACnet)

Official source article: Siemens SSA-180579 ↗. Check the applicable product and release in the original source.

5.3MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 11 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:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 1.06% 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.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Siemens APOGEE PXC Compact (BACnet) 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: As exposure requiresRemediation target: Within 365 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 11 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.

3 current
SSA-180579 · CSAF 2.0 · revision 2 · interimSiemens ProductCERTSSA-180579: Privilege Management Vulnerability and Multiple Nucleus RTOS Vulnerabilities in APOGEE/TALON Field Panels before V3.5.5/V2.8.20
6 known affected

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

  • APOGEE PXC Compact (BACnet)
  • APOGEE PXC Compact (P2 Ethernet)
  • APOGEE PXC Modular (BACnet)
  • APOGEE PXC Modular (P2 Ethernet)
  • TALON TC Compact (BACnet)
  • TALON TC Modular (BACnet)
Summary
The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.
Remediation
Update to V2.8.20 or later version
SSA-669158 · CSAF 2.0 · revision 2 · finalSiemens ProductCERTSSA-669158: DNS Client Vulnerabilities in SIMOTICS CONNECT 400
1 known affected

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

  • SIMOTICS CONNECT 400
Summary
The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.
Remediation
Update to V0.5.0.0 or later version
SSA-705111 · CSAF 2.0 · revision 3 · finalSiemens ProductCERTSSA-705111: Multiple Vulnerabilities (NAME:WRECK) in the DNS Module of Nucleus RTOS
4 known affected

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

  • Nucleus NET
  • Nucleus ReadyStart V3
  • Nucleus ReadyStart V4
  • Nucleus Source Code
Summary
The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.
Remediation
Update to V2017.02.3 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-2021-12569

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 no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 11 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

A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.3), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions < V0.5.0.0), SIMOTICS CONNECT 400 (All versions >= V0.5.0.0 < V1.0.0.0), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.

What

A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.3), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions < V0.5.0.0), SIMOTICS CONNECT 400 (All versions >= V0.5.0.0 < V1.0.0.0), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.

Why

The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.

How

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

What

A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.3), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions < V0.5.0.0), SIMOTICS CONNECT 400 (All versions >= V0.5.0.0 < V1.0.0.0), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.

Why

The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.

How

An attacker operating through a network path may attempt exploitation without authentication or 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.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Use of Insufficiently Random Values → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
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-330 ↗

CWE-330: Use of Insufficiently Random Values. The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.

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:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C

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.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.
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-330
A

Official authority intelligence

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

BSI · German · WID-SEC-2023-1986NAME:WRECK: Mehrere Schwachstellen in TCP/IP Stacks

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Siemens Nucleus Net, Siemens Nucleus RTOS, Microsoft Azure RTOS NetX und Wind River VxWorks ausnutzen, um beliebigen Programmcode mit Administratorrechten auszuführen oder einen Denial of Service zu verursachen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20210428Security Bulletin 28 Apr 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 28 Apr 2021, published on 28 April 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2023-AVI-0633Multiples vulnérabilités dans les produits Siemens

t-portal.siemens.com/productcert/html/ssa-908185.html Bulletin de sécurité Siemens ssa-975961 du 8 août 2023 https://cert-portal.siemens.com/productcert/html/ssa-975961.html Référence CVE CVE-2020-15795 https://www.cve.org/CVERecord?id=CVE-2020-15795 Référence CVE CVE-2020-27009 https://www.cve.org/CVERecord?id=CVE-2020-27009 Référence CVE CVE-2020-27736 https://www.cve.org/CVERecord?id=CVE-2020-27736 Référence CVE CVE-2020-27737 https://www.cve.org/CVERecord?id=CVE-2020-27737 Référence CVE CVE-2020-27738 https://www.cve.org/CVERecord?id=CVE-2020-27738 Référence CVE CVE-2020-28388 https://www.cve.org/CVERecord?id=CVE-2020-28388 Référence CVE CVE-2021-25677 https://www.cve.org/CVERecord?id=CVE-2021-25677 Référence CVE CVE-2021-31239 https://www.cve.org/CVERecord?id=CVE-2021-31239 Référence CVE CVE-2021-41544 https://www.cve.org/CVERecord?id=CVE-2021-41544 Référence CVE CVE-2022-25634 https://www.cve.org/CVERecord?id=CVE-2022-25634 Référence CVE CVE-2022-37971 https://www.cve.org/CVERecord?id=CVE-2022-37971 Référence CVE CVE-2022-39062 https://www.cve.org/CVERecord?id=CVE-2022-39062 Référence CVE CVE-2022-4304 https://www.cve.org/CVERecord?id=CVE-2022-4304 Référence CVE CVE-2022-45937 https://www.cve.org/CVERecord?id=CVE-2022-45937 Référence CVE CVE-2023-0286 https://www.cve.org/CVERecord?id=CVE

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-854Multiples vulnérabilités dans les produits Siemens

d?id=CVE-2020-10054 Référence CVE CVE-2020-15795 https://www.cve.org/CVERecord?id=CVE-2020-15795 Référence CVE CVE-2020-27009 https://www.cve.org/CVERecord?id=CVE-2020-27009 Référence CVE CVE-2020-27736 https://www.cve.org/CVERecord?id=CVE-2020-27736 Référence CVE CVE-2020-27737 https://www.cve.org/CVERecord?id=CVE-2020-27737 Référence CVE CVE-2020-27738 https://www.cve.org/CVERecord?id=CVE-2020-27738 Référence CVE CVE-2020-28388 https://www.cve.org/CVERecord?id=CVE-2020-28388 Référence CVE CVE-2021-25663 https://www.cve.org/CVERecord?id=CVE-2021-25663 Référence CVE CVE-2021-25664 https://www.cve.org/CVERecord?id=CVE-2021-25664 Référence CVE CVE-2021-25677 https://www.cve.org/CVERecord?id=CVE-2021-25677 Référence CVE CVE-2021-27393 https://www.cve.org/CVERecord?id=CVE-2021-27393 Référence CVE CVE-2021-31344 https://www.cve.org/CVERecord?id=CVE-2021-31344 Référence CVE CVE-2021-31345 https://www.cve.org/CVERecord?id=CVE-2021-31345 Référence CVE CVE-2021-31346 https://www.cve.org/CVERecord?id=CVE-2021-31346 Référence CVE CVE-2021-31881 https://www.cve.org/CVERecord?id=CVE-2021-31881 Référence CVE CVE-2021-31882 https://www.cve.org/CVERecord?id=CVE-2021-31882 Référence CVE CVE-2021-31883 https://www.cve.org/CVERecord?id=CVE-2021-31883 Référence CVE CVE-2021-31884 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-255Multiples vulnérabilités dans les produits Siemens

ord?id=CVE-2020-27009 Référence CVE CVE-2020-27736 https://www.cve.org/CVERecord?id=CVE-2020-27736 Référence CVE CVE-2020-27737 https://www.cve.org/CVERecord?id=CVE-2020-27737 Référence CVE CVE-2020-27738 https://www.cve.org/CVERecord?id=CVE-2020-27738 Référence CVE CVE-2020-28385 https://www.cve.org/CVERecord?id=CVE-2020-28385 Référence CVE CVE-2020-7595 https://www.cve.org/CVERecord?id=CVE-2020-7595 Référence CVE CVE-2021-25663 https://www.cve.org/CVERecord?id=CVE-2021-25663 Référence CVE CVE-2021-25664 https://www.cve.org/CVERecord?id=CVE-2021-25664 Référence CVE CVE-2021-25670 https://www.cve.org/CVERecord?id=CVE-2021-25670 Référence CVE CVE-2021-25677 https://www.cve.org/CVERecord?id=CVE-2021-25677 Référence CVE CVE-2021-25678 https://www.cve.org/CVERecord?id=CVE-2021-25678 Référence CVE CVE-2021-27380 https://www.cve.org/CVERecord?id=CVE-2021-27380 Référence CVE CVE-2021-27382 https://www.cve.org/CVERecord?id=CVE-2021-27382 Référence CVE CVE-2021-27389 https://www.cve.org/CVERecord?id=CVE-2021-27389 Référence CVE CVE-2021-27392 https://www.cve.org/CVERecord?id=CVE-2021-27392 Référence CVE CVE-2021-27393 https://www.cve.org/CVERecord?id=CVE-2021-27393 Gestion détaillée du document le 14 avril 2021 Version initiale Alertes Avis Bulletins d’actualités Mentions légales Conditions générales À

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-006157複数のシーメンス製品における不十分なランダム値の使用に関する脆弱性

複数のシーメンス製品には、不十分なランダム値の使用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 V2.8.20 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 22 Apr 2021 · Last source change 3 Aug 2024, 20:11 UTC · CWE-330 · Use of Insufficiently Random Values

CVE recordCVE.org · 5.1
CVSS sourceCNA
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-2021-12569
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    All versions < V3.5.5; All versions < V2.8.20; All versions; All versions < V2017.02.3; All versions < V2017.02.4; All versions < V4.1.0 · 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
    All versions < V3.5.5; All versions < V2.8.20; All versions; All versions < V2017.02.3; All versions < V2017.02.4; All versions < V4.1.0 · Fixed: Update to V2.8.20 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-2021-12569↗Siemens ProductCERT security advisory · Siemens SSA-180579↗CVE authority or vendor reference↗Patch or update 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-2021-25677 · cve.blacktree.nl