BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2021
CVE-2021-37191High confidence

A vulnerability has been identified in SINEMA Remote Connect Server (All versions < V3.0 SP2)

Siemens · SINEMA Remote Connect Server

4.3MediumCVSS 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 1 structured product or package state 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.
  • EPSS is 0.38% 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 SINEMA Remote Connect Server 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 1 structured product or package state 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-334944 · CSAF 2.0 · revision 1 · finalSiemens ProductCERTSSA-334944: Vulnerability in SINEMA Remote Connect Server
1 known affected

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

  • SINEMA Remote Connect Server
Summary
An unauthenticated attacker in the same network of the affected system could brute force the usernames from the affected software.
Remediation
Update to V3.0 SP2 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-2021-23765

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 1 structured product or package state 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 SINEMA Remote Connect Server (All versions < V3.0 SP2). An unauthenticated attacker in the same network of the affected system could brute force the usernames from the affected software.

What

A vulnerability has been identified in SINEMA Remote Connect Server (All versions < V3.0 SP2). An unauthenticated attacker in the same network of the affected system could brute force the usernames from the affected software.

Why

The product does not properly limit the number or frequency of interactions that it has with an actor, such as the number of incoming requests.

How

An attacker operating through the affected interface 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 SINEMA Remote Connect Server (All versions < V3.0 SP2). An unauthenticated attacker in the same network of the affected system could brute force the usernames from the affected software.

Why

The product does not properly limit the number or frequency of interactions that it has with an actor, such as the number of incoming requests.

How

An attacker operating through the affected interface 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
the affected interface → Improper Control of Interaction Frequency → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Unspecified
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-799 ↗

CWE-799: Improper Control of Interaction Frequency. The product does not properly limit the number or frequency of interactions that it has with an actor, such as the number of incoming requests.

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

Common Vulnerability Scoring System 3.1: 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.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.CLowConfidentiality impact: A successful attack can cause a limited loss.INoneIntegrity impact: No direct loss is represented by this metric.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.
UnauthenticatedCWE-799
A

Official authority intelligence

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

Cyber Security Agency of Singapore · English · CSA-SB-20210915Security Bulletin 15 Sep 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 15 Sep 2021, published on 15 September 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-706Multiples vulnérabilités dans les produits Siemens

d?id=CVE-2021-37174 Référence CVE CVE-2021-37175 https://www.cve.org/CVERecord?id=CVE-2021-37175 Référence CVE CVE-2021-37176 https://www.cve.org/CVERecord?id=CVE-2021-37176 Référence CVE CVE-2021-37177 https://www.cve.org/CVERecord?id=CVE-2021-37177 Référence CVE CVE-2021-37181 https://www.cve.org/CVERecord?id=CVE-2021-37181 Référence CVE CVE-2021-37183 https://www.cve.org/CVERecord?id=CVE-2021-37183 Référence CVE CVE-2021-37184 https://www.cve.org/CVERecord?id=CVE-2021-37184 Référence CVE CVE-2021-37186 https://www.cve.org/CVERecord?id=CVE-2021-37186 Référence CVE CVE-2021-37190 https://www.cve.org/CVERecord?id=CVE-2021-37190 Référence CVE CVE-2021-37191 https://www.cve.org/CVERecord?id=CVE-2021-37191 Référence CVE CVE-2021-37192 https://www.cve.org/CVERecord?id=CVE-2021-37192 Référence CVE CVE-2021-37193 https://www.cve.org/CVERecord?id=CVE-2021-37193 Référence CVE CVE-2021-37200 https://www.cve.org/CVERecord?id=CVE-2021-37200 Référence CVE CVE-2021-37201 https://www.cve.org/CVERecord?id=CVE-2021-37201 Référence CVE CVE-2021-37202 https://www.cve.org/CVERecord?id=CVE-2021-37202 Référence CVE CVE-2021-37203 https://www.cve.org/CVERecord?id=CVE-2021-37203 Référence CVE CVE-2021-37206 https://www.cve.org/CVERecord?id=CVE-2021-37206 Référence CVE CVE-2021-40354 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-011705SINEMA Remote Connect Server におけるインタラクション頻度の制御に関する脆弱性

SINEMA Remote Connect Server には、インタラクション頻度の制御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
SINEMA Remote Connect Server
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.
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 14 Sept 2021 · Last source change 23 Apr 2025, 19:28 UTC · CWE-799 · Improper Control of Interaction Frequency

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-2021-23765
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. Remediation statusRemediation status changed from Patch available to Mitigation available.
    Before
    Patch available
    After
    Mitigation available
    Siemens ProductCERT ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
Remediation guidance recorded
ENISA EUVD · EUVD-2021-23765↗CVE authority or vendor 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-2021-37191 · cve.blacktree.nl