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 6.25% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2017
CVE-2015-8138High confidence
NTP before 4.2.8p6 and 4.3.x before 4.3.90 allows remote attackers to bypass the origin timestamp validation via a packet with an origin timestamp set to zero
Unknown · Unknown
Official source article: Siemens SSA-497656 ↗. Check the applicable product and release in the original source.
5.3MediumCVSS 3.0
Patch only the product branches with a verified fix
Fix availability varies by productMedium 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 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 severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Apply the linked authoritative mitigation while planning the permanent fix.
- 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.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- 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: 4 affected or under-investigation product states without a fixed product state in the same current advisory
- Siemens ProductCERT: 1 affected or under-investigation product state 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.
SSA-497656 · CSAF 2.0 · revision 2 · finalSiemens ProductCERTSSA-497656: Multiple NTP Vulnerabilities in TIM 4R-IE Devices
The vendor explicitly identifies these products as affected by this CVE.
- SIPLUS NET TIM 4R-IE (6AG1800-4BA00-7AA0)
- SIPLUS NET TIM 4R-IE DNP3 (6AG1803-4BA00-7AA0)
- TIM 4R-IE (6NH7800-4BA00)
- TIM 4R-IE DNP3 (6NH7803-4BA00-0AA0)
- Summary
- NTP before 4.2.8p6 and 4.3.x before 4.3.90 allows remote attackers to bypass the origin timestamp validation via a packet with an origin timestamp set to zero.
- Remediation
- Deactivate NTP-based time syncronization of the device, if enabled. The feature is disabled by default.
SSA-211752 · CSAF 2.0 · revision 2 · finalSiemens ProductCERTSSA-211752: Multiple NTP-Client Related Vulnerabilities in SIMATIC CP 443-1 OPC UA
The vendor explicitly identifies these products as affected by this CVE.
- SIMATIC CP 443-1 OPC UA (6GK7443-1UX00-0XE0)
- Summary
- NTP before 4.2.8p6 and 4.3.x before 4.3.90 allows remote attackers to bypass the origin timestamp validation via a packet with an origin timestamp set to zero.
- Remediation
- Deactivate NTP-based time synchronization of the device, if enabled. The feature is disabled by default
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 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
NTP before 4.2.8p6 and 4.3.x before 4.3.90 allows remote attackers to bypass the origin timestamp validation via a packet with an origin timestamp set to zero.
What
NTP before 4.2.8p6 and 4.3.x before 4.3.90 allows remote attackers to bypass the origin timestamp validation via a packet with an origin timestamp set to zero.
Why
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
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
NTP before 4.2.8p6 and 4.3.x before 4.3.90 allows remote attackers to bypass the origin timestamp validation via a packet with an origin timestamp set to zero.
Why
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
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 → Improper Input Validation → 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-20 ↗
CWE-20: Improper Input Validation. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:NCommon Vulnerability Scoring System 3.0: 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.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.
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
- 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
- Deactivate NTP-based time syncronization of the device, if enabled. The feature is disabled by default.
04
Evidence and provenance
Published 30 Jan 2017 · Last source change 6 Aug 2024, 08:13 UTC · CWE-20 · Improper Input Validation
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-09-01
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2015-8028
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
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
- ENISA EUVD mappingEUVD-2015-8028 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2015-8028"}
- Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: support.ntp.org/SecurityNotice; removed vendor advisory: debian.org/dsa-3629; removed vendor advisory: lists.fedoraproject.org/176434.html; 16 further removals.support.ntp.org ↗
- Before
- vendor advisory: debian.org/dsa-3629 · vendor advisory: lists.fedoraproject.org/176434.html · vendor advisory: lists.fedoraproject.org/177507.html · 15 more references
- After
- vendor advisory: support.ntp.org/SecurityNotice
- SeveritySeverity changed from Unknown to Medium.NIST NVD ↗
- Before
- Unknown
- After
- Medium
- CVSS scoreCVSS score changed from not recorded to 5.3 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N).NIST NVD ↗
- Before
- not recorded
- After
- 5.3 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
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.