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Full vulnerability report · 2017
CVE-2015-7855High confidence

Affected product: Improper Input Validation

Unknown · Unknown

Official source article: Siemens SSA-497656 ↗. Check the applicable product and release in the original source.

6.5MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 4 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 severityMediumOperational priority:High, raised one band.upgradedsince 6 Aug 2024

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • EPSS is 31.07% 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.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Unknown Unknown 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 4 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-497656 · CSAF 2.0 · revision 2 · finalSiemens ProductCERTSSA-497656: Multiple NTP Vulnerabilities in TIM 4R-IE Devices
4 known affected

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
The decodenetnum function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (assertion failure) via a 6 or mode 7 packet containing a long data value.
Remediation
Deactivate NTP-based time syncronization of the device, if enabled. The feature is disabled by default.
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-2015-7753

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 public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 4 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

The decodenetnum function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (assertion failure) via a 6 or mode 7 packet containing a long data value.

What

The decodenetnum function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (assertion failure) via a 6 or mode 7 packet containing a long data value.

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 with low privileges. If successful, the issue may disrupt the affected service.

What

The decodenetnum function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (assertion failure) via a 6 or mode 7 packet containing a long data value.

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 with low privileges. 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.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Improper Input Validation → disrupt the affected service
Attack surface
Network
Privileges required
Low: a basic authenticated account is required
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:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Common 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.PRLowPrivileges required: The attacker needs basic user-level 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.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
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.
NetworkDenial of serviceCWE-20Public exploit reference
A

Official authority intelligence

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

Canadian Centre for Cyber Security · English · AV17-067Rockwell Automation Stratix 5900 security update

0 industrial router products. The severity of the vulnerabilities range from high to critical, and exploitation could allow an unprivileged attacker to remotely execute code and/or create denial of service conditions. Affected software versions: Stratix 5900 version 15.6.3 EA and earlier CVE References: CVE-2016-6380, CVE-2016-6393, CVE-2016-6384, CVE-2016-6381, CVE-2016-6382, CVE-2016-6415, CVE-2016-1409, CVE-2016-1350, CVE-2016-1344, CVE-2015-7691, CVE-2015-7692, CVE-2015-7701, CVE-2015-7702, CVE-2015-7703, CVE-2015-7704, CVE-2015-7705, CVE-2015-7848, CVE-2015-7849, CVE-2015-7850, CVE-2015-7851, CVE-2015-7852, CVE-2015-7853, CVE-2015-7854, CVE-2015-7855, CVE-2015-7871, CVE-2015-1798, CVE-2015-0642, CVE-2015-0643, CVE-2015-0646, CVE-2015-0207, CVE-2015-0209, CVE-2015-0285, CVE-2015-0287, CVE-2015-0288, CVE-2015-0289, CVE-2015-0290, CVE-2015-0291, CVE-2015-0292, CVE-2015-0293, CVE-2015-1787, CVE-2014-3566, CVE-2014-3359, CVE-2014-3355, CVE-2014-3361, CVE-2014-3354, CVE-2014-3360, CVE-2014-3299, CVE-2010-5298, CVE-2014-0076, CVE-2014-0195, CVE-2014-0198, CVE-2014-0221, CVE-2014-0224, CVE-2014-3470, CVE-2014-2113, CVE-2014-2108, CVE-2014-2109, CVE-2014-2111, CVE-2014-2106, CVE-2014-2112 Suggested Action CCIRC recommends that system administrators test and deploy the vendor-released updates to a

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-255Multiples vulnérabilités dans les produits Siemens

7.pdf Bulletin de sécurité Siemens ssa-788287 du 13 avril 2021 https://cert-portal.siemens.com/productcert/pdf/ssa-788287.pdf Bulletin de sécurité Siemens ssa-844761 du 13 avril 2021 https://cert-portal.siemens.com/productcert/pdf/ssa-844761.pdf Bulletin de sécurité Siemens ssa-853866 du 13 avril 2021 https://cert-portal.siemens.com/productcert/pdf/ssa-853866.pdf Bulletin de sécurité Siemens ssa-983300 du 13 avril 2021 https://cert-portal.siemens.com/productcert/pdf/ssa-983300.pdf Référence CVE CVE-2015-5219 https://www.cve.org/CVERecord?id=CVE-2015-5219 Référence CVE CVE-2015-7705 https://www.cve.org/CVERecord?id=CVE-2015-7705 Référence CVE CVE-2015-7855 https://www.cve.org/CVERecord?id=CVE-2015-7855 Référence CVE CVE-2015-7871 https://www.cve.org/CVERecord?id=CVE-2015-7871 Référence CVE CVE-2015-7973 https://www.cve.org/CVERecord?id=CVE-2015-7973 Référence CVE CVE-2015-7974 https://www.cve.org/CVERecord?id=CVE-2015-7974 Référence CVE CVE-2015-7977 https://www.cve.org/CVERecord?id=CVE-2015-7977 Référence CVE CVE-2015-7979 https://www.cve.org/CVERecord?id=CVE-2015-7979 Référence CVE CVE-2015-8138 https://www.cve.org/CVERecord?id=CVE-2015-8138 Référence CVE CVE-2015-8214 https://www.cve.org/CVERecord?id=CVE-2015-8214 Référence CVE CVE-2016-1547 https://www.cve.org/CVERecord?id=CVE-2016-1547 Ré

Official advisory ↗
CERT-FR · French · CERTFR-2015-AVI-449Multiples vulnérabilités dans NTP

De multiples vulnérabilités ont été corrigées dans NTP . Elles permettent à un attaquant de provoquer un déni de service à distance et une atteinte à la confidentialité des données.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2015-007707NTP における入力確認に関する脆弱性

NTP には、入力確認に関する脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-4561NTP 다중 취약점 보안 업데이트 권고

decodenetnum()함수에서 위조된 값에 대해 FAIL 반환하는 대신 오류 값을 발생하는 취약점(CVE-2015-7855)

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
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
Deactivate NTP-based time syncronization of the device, if enabled. The feature is disabled by default.
04

Evidence and provenance

Published 7 Aug 2017 · Last source change 6 Aug 2024, 08:06 UTC · CWE-20 · Improper Input Validation

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 2026-09-01
European sourceENISA EUVD · EUVD-2015-7753
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

What changed after publication

View recent updates ↗
  1. ENISA EUVD mappingEUVD-2015-7753 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2015-7753"}
    ENISA EUVD ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added patch: support.ntp.org/NtpBug2922; added remediation: support.ntp.org/NtpBug2922; removed vendor advisory: debian.org/dsa-3388; removed vendor advisory: security.gentoo.org/201607-15.
    Before
    vendor advisory: debian.org/dsa-3388 · vendor advisory: security.gentoo.org/201607-15
    After
    patch: support.ntp.org/NtpBug2922 · remediation: support.ntp.org/NtpBug2922
    support.ntp.org ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    n/a · 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.
    CNA ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    support.ntp.org ↗
  5. SeveritySeverity changed from Unknown to Medium.
    Before
    Unknown
    After
    Medium
    NIST NVD ↗
  6. CVSS scoreCVSS score changed from not recorded to 6.5 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
    Before
    not recorded
    After
    6.5 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
    NIST NVD ↗
  7. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2015-7753↗Vendor CSAF · Siemens ProductCERT · Siemens SSA-497656↗Patch or update reference↗Public exploit 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-2015-7855 · cve.blacktree.nl