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Full vulnerability report · 2025
CVE-2025-40743High confidence

Siemens SINUMERIK 828D PPU.4 — Authentication Bypass Using an Alternate Path or Channel

Siemens · SINUMERIK 828D PPU.4

Official source article: Siemens SSA-177847 ↗. 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 7 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.
  • EPSS is 0.24% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Siemens SINUMERIK 828D PPU.4 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 7 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-177847 · CSAF 2.0 · revision 1 · interimSiemens ProductCERTSSA-177847: Improper VNC Password Check Vulnerability in SINUMERIK Controllers
7 known affected

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

  • SINUMERIK 828D PPU.4
  • SINUMERIK 828D PPU.5
  • SINUMERIK 840D sl
  • SINUMERIK MC
  • SINUMERIK MC V1.15
  • SINUMERIK ONE
  • SINUMERIK ONE V6.15
Summary
The affected application improperly validates authentication for its VNC access service, allowing access with insufficient password verification. This could allow an attacker to gain unauthorized remote access and potentially compromise system confidentiality, integrity, or availability.
Remediation
Update to V1.15 SP5 or later version Updated software version can be obtained from Siemens customer support or a local partner.
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-2025-24245

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 7 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 SINUMERIK 828D PPU.4 (All versions < V4.95 SP5), SINUMERIK 828D PPU.5 (All versions < V5.25 SP1), SINUMERIK 840D sl (All versions < V4.95 SP5), SINUMERIK MC (All versions < V1.25 SP1), SINUMERIK MC V1.15 (All versions < V1.15 SP5), SINUMERIK ONE (All versions < V6.25 SP1), SINUMERIK ONE V6.15 (All versions < V6.15 SP5). The affected application improperly validates authentication for its VNC access service, allowing access with insufficient password verification. This could allow an attacker to gain unauthorized remote access and potentially compromise system confidentiality, integrity, or availability.

What

A vulnerability has been identified in SINUMERIK 828D PPU.4 (All versions < V4.95 SP5), SINUMERIK 828D PPU.5 (All versions < V5.25 SP1), SINUMERIK 840D sl (All versions < V4.95 SP5), SINUMERIK MC (All versions < V1.25 SP1), SINUMERIK MC V1.15 (All versions < V1.15 SP5), SINUMERIK ONE (All versions < V6.25 SP1), SINUMERIK ONE V6.15 (All versions < V6.15 SP5). The affected application improperly validates authentication for its VNC access service, allowing access with insufficient password verification. This could allow an attacker to gain unauthorized remote access and potentially compromise system confidentiality, integrity, or availability.

Why

The product requires authentication, but the product has an alternate path or channel that does not require authentication.

How

An attacker operating through an adjacent network 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 SINUMERIK 828D PPU.4 (All versions < V4.95 SP5), SINUMERIK 828D PPU.5 (All versions < V5.25 SP1), SINUMERIK 840D sl (All versions < V4.95 SP5), SINUMERIK MC (All versions < V1.25 SP1), SINUMERIK MC V1.15 (All versions < V1.15 SP5), SINUMERIK ONE (All versions < V6.25 SP1), SINUMERIK ONE V6.15 (All versions < V6.15 SP5). The affected application improperly validates authentication for its VNC access service, allowing access with insufficient password verification. This could allow an attacker to gain unauthorized remote access and potentially compromise system confidentiality, integrity, or availability.

Why

The product requires authentication, but the product has an alternate path or channel that does not require authentication.

How

An attacker operating through an adjacent network 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
an adjacent network → Authentication Bypass Using an Alternate Path or Channel → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Adjacent
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-288 ↗

CWE-288: Authentication Bypass Using an Alternate Path or Channel. The product requires authentication, but the product has an alternate path or channel that does not require authentication.

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

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVAdjacentAttack vector: The attacker must be on an adjacent or logically close 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.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VALowVulnerable-system availability: A successful attack can cause a limited 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.
UnauthenticatedCWE-288
A

Official authority intelligence

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

NCSC-NL · Dutch · NCSC-2025-0246Kwetsbaarheden verholpen in Siemens producten

De kwetsbaarheden stellen een kwaadwillende mogelijk in staat aanvallen uit te voeren die kunnen leiden tot de volgende categorieën schade: * Denial-of-Service (DoS) * Cross-Site Scripting * Manipulatie van gegevens * Omzeilen van een beveiligingsmaatregel * (Remote) code execution (SYSTEM rechten) * (Remote) code execution (Gebruikersrechten) * Toegang tot gevoelige gegevens * Verhogen van rechten De kwaadwillende heeft hiervoor toegang nodig tot de productieomgeving. Het is goed gebruik een dergelijke omgeving niet publiek toegankelijk te hebben.

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. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 12 Aug 2025 · Last source change 13 Aug 2025, 20:18 UTC · CWE-288 · Authentication Bypass Using an Alternate Path or Channel

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-2025-24245
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. 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-2025-24245↗CVE authority or vendor reference · Siemens SSA-177847↗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-2025-40743 · cve.blacktree.nl