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 2.05% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2021
CVE-2020-35685High confidence
As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones
Unknown · Unknown
9.1CriticalCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productCritical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 5 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityCritical→Operational priority:Critical, unchanged from published severity.unchanged
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
- Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 5 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Siemens ProductCERT: 5 affected or under-investigation product states without a fixed product state in the same current advisory
Direct vendor intelligence
2 currentAuthoritative 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.
SEVD-2021-217-01 · CSAF 2.0 · revision 5.0.0 · finalSchneider Electric CPCERTNicheStack TCP/IP Vulnerabilities (INFRA:HALT) in Lexium ILE, ILA, ILS, and Communication Option Boards for Altivar and Lexium32 drives
The vendor explicitly identifies these products as affected by this CVE.
- Schneider Electric Lexium ILE ILA ILS communication drive version 01.110 and prior
- Schneider Electric Altivar 32/320/340/600/900 Profinet communication module (VW3A3627)
- Schneider Electric Altivar 32/320 and Lexium 32 Ethernet TCP/IP communication module (VW3A3616) versions prior to V1.20IE01
- Schneider Electric Altivar 61/71 Profinet communication card (VW3A3327) All versions
- Summary
- Five of the 14 vulnerabilities disclosed by researchers in the NicheStack TCP/IP component impact Schneider Electric’s Lexium ILE, ILA, ILS, Altivar Profinet Communication Module (VW3A3627), Altivar and Lexium Ethernet TCP/IP Communication Module (VW3A3616), and Altivar Profinet - Communication Card (VW3A3327). Additional information vulnerability details can be found at https://us-cert.cisa.gov/ics/advisories/icsa-21-217-01.
- Remediation
- V01.111 of Lexium ILE, ILA, ILS communication module includes a fix for these vulnerabilities. Reboot is needed. Please contact your local Schneider Electric technical support for more information on how to get the firmware and how to upgrade the communication firmware module.
SSA-789208 · CSAF 2.0 · revision 3 · finalSiemens ProductCERTSSA-789208: Multiple Vulnerabilities (INFRA:HALT) in Interniche IP-Stack based Low Voltage Devices
The vendor explicitly identifies these products as affected by this CVE.
- SENTRON 3WA COM190
- SENTRON 3WL COM35
- SENTRON 7KM PAC Switched Ethernet PROFINET Expansion Module (7KM9300-0AE00-0AA0)
- SENTRON 7KM PAC Switched Ethernet PROFINET Expansion Module (7KM9300-0AE01-0AA0)
- SENTRON 7KM PAC Switched Ethernet PROFINET Expansion Module (7KM9300-0AE02-0AA0)
- Summary
- TCP ISNs are generated in a predictable manner.
- Remediation
- Update to V2.0.0 or later version
Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 5 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
An issue was discovered in HCC Nichestack 3.0. The code that generates Initial Sequence Numbers (ISNs) for TCP connections derives the ISN from an insufficiently random source. As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones. (Proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.)
What
An issue was discovered in HCC Nichestack 3.0. The code that generates Initial Sequence Numbers (ISNs) for TCP connections derives the ISN from an insufficiently random source. As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones. (Proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.)
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
An issue was discovered in HCC Nichestack 3.0. The code that generates Initial Sequence Numbers (ISNs) for TCP connections derives the ISN from an insufficiently random source. As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones. (Proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.)
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 No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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:H/I:H/A:NCommon 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.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major 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.
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
- Schneider Electric Lexium ILE ILA ILS communication drive version 01.110 and prior
- Schneider Electric Altivar 32/320/340/600/900 Profinet communication module (VW3A3627)
- Schneider Electric Altivar 32/320 and Lexium 32 Ethernet TCP/IP communication module (VW3A3616) versions prior to V1.20IE01
- Schneider Electric Altivar 61/71 Profinet communication card (VW3A3327) All versions
- Fixed
- 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
- A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.
04
Evidence and provenance
Published 19 Aug 2021 · Last source change 4 Aug 2024, 17:09 UTC · CWE-330 · Use of Insufficiently Random Values
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2020-23344
Product sourceVendor CSAF · Schneider Electric CPCERT
Remediation sourceVendor CSAF · Schneider Electric CPCERT
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
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.Schneider Electric CPCERT ↗
- Before
- n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- n/a · Fixed: V01.111 of Lexium ILE, ILA, ILS communication module includes a fix for these vulnerabilities. Reboot is needed. Please contact your local Schneider Electric technical support for more information on how to get the firmware and how to upgrade the communication firmware module.
- Remediation statusRemediation status changed from Mitigation available to Patch available.Schneider Electric CPCERT ↗
- Before
- Mitigation available
- After
- Patch available
CVE published
Mitigation reference recorded
Fixed release recorded from official guidance
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.