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Full vulnerability report · 2025
CVE-2025-40820High confidence

This could allow an unauthenticated remote attacker e.g

Siemens · SIDOOR ATD430W

Official source article: Siemens SSA-915282 ↗. Check the applicable product and release in the original source.

8.7HighCVSS 4.0
Recommended action
Patch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 171 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 severityHighOperational priority:High, 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 0.49% 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 SIDOOR ATD430W 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 171 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-915282 · CSAF 2.0 · revision 1 · interimSiemens ProductCERTSSA-915282: Denial of service Vulnerability in Interniche IP-Stack based Industrial Devices
171 known affected

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

  • SIDOOR ATD430W
  • SIDOOR ATE530G COATED (6FB1221-5SM10-7BP0)
  • SIDOOR ATE530S COATED
  • SIMATIC CFU DIQ (6ES7655-5PX31-1XX0)
  • SIMATIC CFU PA (6ES7655-5PX11-0XX0)
  • SIMATIC CFU PA (6ES7655-5PX11-1XX0)
  • SIMATIC ET 200AL IM 157-1 PN (6ES7157-1AB00-0AB0)
  • SIMATIC ET 200clean, CM 8x IO-Link (6ES7148-7JH00-0BB0)
  • SIMATIC ET 200clean, DI 16x24VDC (6ES7141-7BH00-0BB0)
  • SIMATIC ET 200clean, DIQ 16x24VDC/0,5A (6ES7143-7BH00-0BB0)
  • SIMATIC ET 200eco PN, AI 8xRTD/TC, M12-L (6ES7144-6JF00-0BB0)
  • SIMATIC ET 200eco PN, CM 4x IO-Link, M12-L (6ES7148-6JE00-0BB0)
Summary
Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range. This could allow an unauthenticated remote attacker e.g. to interfere with connection setup, potentially leading to a denial of service. The attack succeeds only if an attacker can inject IP packets with spoofed addresses at precisely timed moments, and it affects only TCP-based services.
Remediation
Update to V1.3 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-2025-201923

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

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 171 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

Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range. This could allow an unauthenticated remote attacker e.g. to interfere with connection setup, potentially leading to a denial of service. The attack succeeds only if an attacker can inject IP packets with spoofed addresses at precisely timed moments, and it affects only TCP-based services.

What

Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range. This could allow an unauthenticated remote attacker e.g. to interfere with connection setup, potentially leading to a denial of service. The attack succeeds only if an attacker can inject IP packets with spoofed addresses at precisely timed moments, and it affects only TCP-based services.

Why

The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range. This could allow an unauthenticated remote attacker e.g. to interfere with connection setup, potentially leading to a denial of service. The attack succeeds only if an attacker can inject IP packets with spoofed addresses at precisely timed moments, and it affects only TCP-based services.

Why

The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

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 → Improper Verification of Source of a Communication Channel → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-940 ↗

CWE-940: Improper Verification of Source of a Communication Channel. The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: 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.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: 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.
NetworkUnauthenticatedDenial of serviceCWE-940
A

Official authority intelligence

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

BSI · German · WID-SEC-2025-2788Siemens SIMATIC S7 Produkte: Schwachstelle ermöglicht Denial of Service

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Siemens SIMATIC S7 ausnutzen, um einen Denial of Service Angriff durchzuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20251210Security Bulletin 10 Dec 2025

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 10 Dec 2025, published on 10 December 2025. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-1083Multiples vulnérabilités dans les produits Siemens

la politique de sécurité Déni de service à distance Exécution de code arbitraire à distance Injection de code indirecte à distance (XSS) Injection de requêtes illégitimes par rebond (CSRF) Systèmes affectés SICAM T versions antérieures à 3.0 SIMATIC CFU DIQ (6ES7655-5PX31-1XX0) versions antérieures à 2.0.0 SIMATIC CFU PA (6ES7655-5PX11-0XX0) versions antérieures à 2.0.0 SIMATIC CFU PA (6ES7655-5PX11-1XX0) versions antérieures à 2.0.0 SIMATIC CN 4100 versions antérieures à 4.0.1 SIMATIC ET 200AL IM 157-1 PN (6ES7157-1AB00-0AB0) toutes versions. L'éditeur indique que le produit ne bénéficiera pas de correctif de sécurité pour la vulnérabilité CVE-2025-40820. SIMATIC ET 200clean, CM 8x IO-Link (6ES7148-7JH00-0BB0) toutes versions. L'éditeur indique que le produit ne bénéficiera pas de correctif de sécurité pour la vulnérabilité CVE-2025-40820. SIMATIC ET 200clean, DI 16x24VDC (6ES7141-7BH00-0BB0) toutes versions. L'éditeur indique que le produit ne bénéficiera pas de correctif de sécurité pour la vulnérabilité CVE-2025-40820. SIMATIC ET 200clean, DIQ 16x24VDC/0,5A (6ES7143-7BH00-0BB0) toutes versions. L'éditeur indique que le produit ne bénéficiera pas de correctif de sécurité pour la vulnérabilité CVE-2025-40820. SIMATIC ET 200eco PN, AI 8xRTD/TC, M12-L (6ES7144-6JF00-0BB0) versions supérieures

Official advisory ↗
NCSC-NL · Dutch · NCSC-2025-0382Kwetsbaarheden verholpen in Siemens producten

The document outlines a vulnerability in certain products that lack TCP sequence number validation, enabling unauthenticated remote attackers to disrupt TCP-based services through the injection of spoofed IP packets.

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
No fixed version is explicitly recorded in the structured CVE data.
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 9 Dec 2025 · Last source change 9 Dec 2025, 15:55 UTC · CWE-940 · Improper Verification of Source of a Communication Channel

CVE recordCVE.org · 5.2
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-2025-201923
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCNA
NVD statusNVD not scheduled

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: removed patch: cert-portal.siemens.com/ssa-915282.html; removed remediation: cert-portal.siemens.com/ssa-915282.html.
    Before
    patch: cert-portal.siemens.com/ssa-915282.html · remediation: cert-portal.siemens.com/ssa-915282.html
    After
    no authoritative guidance recorded
    CNA ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    < *; < V2.0.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    SIDOOR ATD430W: < *; SIDOOR ATE530G COATED: < *; SIDOOR ATE530S COATED: < *; SIMATIC CFU DIQ: < V2.0.0; SIMATIC CFU PA: < V2.0.0; SIMATIC ET 200AL IM 157-1 PN: < *; SIMATIC ET 200clean, CM 8x IO-Link: < *; SIMATIC ET 200clean, DI 16x24VDC: < *; SIMATIC ET 200clean, DIQ 16x24VDC/0,5A: < *; SIMATIC ET 200eco PN, AI 8xRTD/TC, M12-L: V5.1.1 < *; SIMATIC ET 200eco PN, CM 4x IO-Link, M12-L: V5.1.1 < *; SIMATIC ET 200eco PN, CM 8x IO-Link, M12-L: V5.1.1 < *; SIMATIC ET 200eco PN, DI 16x24VDC, M12-L: V5.1.1 < *; SIMATIC ET 200eco PN, DI 8x24VDC, M12-L: V5.1.1 < *; SIMATIC ET 200eco PN, DIQ 16x24VDC/2A, M12-L: V5.1.1 < *; SIMATIC ET 200eco PN, DQ 8x24VDC/0,5A, M12-L: V5.1.1 < *; SIMATIC ET 200eco PN, DQ 8x24VDC/2A, M12-L: V5.1.1 < *; SIMATIC ET 200MP IM 155-5 PN HF: V4.2.0 < *; SIMATIC ET 200pro IM 154-8 PN/DP CPU: < *; SIMATIC ET 200pro IM 154-8F PN/DP CPU: < *; SIMATIC ET 200pro IM 154-8FX PN/DP CPU: < *; SIMATIC ET 200S IM 151-8 PN/DP CPU: < *; SIMATIC ET 200S IM 151-8F PN/DP CPU: < *; SIMATIC ET 200SP CPU 1510SP F-1 PN: < *; SIMATIC ET 200SP CPU 1510SP-1 PN: < *; SIMATIC ET 200SP CPU 1512SP F-1 PN: < *; SIMATIC ET 200SP CPU 1512SP-1 PN: < *; SIMATIC ET 200SP IM 155-6 MF HF: < *; SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants): < V1.3; SIMATIC ET 200SP IM 155-6 PN HF: V4.2.0 < *; SIMATIC ET 200SP IM 155-6 PN/2 HF: V4.2.0 < *; SIMATIC ET 200SP IM 155-6 PN/3 HF: V4.2.0 < *; SIMATIC PN/MF Coupler: < *; SIMATIC PN/PN Coupler: < V6.0.0; SIMATIC Power Line Booster PLB, Base Module: < *; SIMATIC Power Line Booster PLB, Modem Module ST: < *; SIMATIC S7-1200 CPU 1211C AC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1211C DC/DC/DC: < V4.4.0; SIMATIC S7-1200 CPU 1211C DC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1212C AC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1212C DC/DC/DC: < V4.4.0; SIMATIC S7-1200 CPU 1212C DC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1212FC DC/DC/DC: < V4.4.0; SIMATIC S7-1200 CPU 1212FC DC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1214C AC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1214C DC/DC/DC: < V4.4.0; SIMATIC S7-1200 CPU 1214C DC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1214FC DC/DC/DC: < V4.4.0; SIMATIC S7-1200 CPU 1214FC DC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1215C AC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1215C DC/DC/DC: < V4.4.0; SIMATIC S7-1200 CPU 1215C DC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1215FC DC/DC/DC: < V4.4.0; SIMATIC S7-1200 CPU 1215FC DC/DC/Rly: < V4.4.0; SIMATIC S7-1200 CPU 1217C DC/DC/DC: < V4.4.0; SIMATIC S7-1500 CPU 1511-1 PN: < *; SIMATIC S7-1500 CPU 1511F-1 PN: < *; SIMATIC S7-1500 CPU 1513-1 PN: < *; SIMATIC S7-1500 CPU 1513F-1 PN: < *; SIMATIC S7-1500 CPU 1515-2 PN: < *; SIMATIC S7-1500 CPU 1515F-2 PN: < *; SIMATIC S7-1500 CPU 1516-3 PN/DP: < *; SIMATIC S7-1500 CPU 1516F-3 PN/DP: < *; SIMATIC S7-200 SMART CPU CR40: < *; SIMATIC S7-200 SMART CPU CR60: < *; SIMATIC S7-200 SMART CPU SR20: < *; SIMATIC S7-200 SMART CPU SR30: < *; SIMATIC S7-200 SMART CPU SR40: < *; SIMATIC S7-200 SMART CPU SR60: < *; SIMATIC S7-200 SMART CPU ST20: < *; SIMATIC S7-200 SMART CPU ST30: < *; SIMATIC S7-200 SMART CPU ST40: < *; SIMATIC S7-200 SMART CPU ST60: < *; SIMATIC S7-300 CPU 314C-2 PN/DP: < *; SIMATIC S7-300 CPU 315-2 PN/DP: < *; SIMATIC S7-300 CPU 315F-2 PN/DP: < *; SIMATIC S7-300 CPU 315T-3 PN/DP: < *; SIMATIC S7-300 CPU 317-2 PN/DP: < *; SIMATIC S7-300 CPU 317F-2 PN/DP: < *; SIMATIC S7-300 CPU 317T-3 PN/DP: < *; SIMATIC S7-300 CPU 317TF-3 PN/DP: < *; SIMATIC S7-300 CPU 319-3 PN/DP: < *; SIMATIC S7-300 CPU 319F-3 PN/DP: < *; SIMATIC S7-400 CPU 412-2 PN V7: < *; SIMATIC S7-400 CPU 414-3 PN/DP V7: < *; SIMATIC S7-400 CPU 414F-3 PN/DP V7: < *; SIMATIC S7-400 CPU 416-3 PN/DP V7: < *; SIMATIC S7-400 CPU 416F-3 PN/DP V7: < *; SIMATIC S7-400 H V6 CPU family (incl. SIPLUS variants): < *; SIMATIC S7-410 V10 CPU family (incl. SIPLUS variants): < V10.2; SIMATIC S7-410 V8 CPU family (incl. SIPLUS variants): < V8.3; SIMATIC TDC CP51M1: < *; SIMATIC TDC CPU555: < *; SIMOCODE pro V Ethernet/IP (incl. SIPLUS variants): < *; 51 additional product groups retained in the authoritative source · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  3. Remediation statusRemediation status changed from Mitigation available to Awaiting fix.
    Before
    Mitigation available
    After
    Awaiting fix
    CNA ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Mitigation available.
    Before
    Awaiting fix
    After
    Mitigation available
    Siemens ProductCERT ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Remediation guidance recorded
ENISA EUVD · EUVD-2025-201923↗CVE authority or vendor reference · Siemens SSA-915282↗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-2025-40820 · cve.blacktree.nl