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Full vulnerability report · 2017
CVE-2017-12336High confidence

n/a Cisco NX-OS: Improper Input Validation

Unknown · Cisco NX-OS

Official source article: Cisco CISCO-SA-20171129-NXOS5 ↗. Check the applicable product and release in the original source.

4.2MediumCVSS 3.0
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Low, lowered one band.downgradedsince 5 Aug 2024

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 0.43% for the current model date.

Compensating controls

  • 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 Unknown Cisco NX-OS and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  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: No default targetRemediation target: Normal maintenance

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.

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-2017-3909

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 actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Fix not verified
01

What, why and how

A vulnerability in the TCL scripting subsystem of Cisco NX-OS System Software could allow an authenticated, local attacker to escape the interactive TCL shell and gain unauthorized access to the underlying operating system of the device. The vulnerability exists due to insufficient input validation of user-supplied files passed to the interactive TCL shell of the affected device. An attacker could exploit this vulnerability to escape the scripting sandbox and execute arbitrary commands on the underlying operating system with the privileges of the authenticated user. To exploit this vulnerability, an attacker must have local access and be authenticated to the targeted device with administrative or tclsh execution privileges. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 5000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, Unified Computing System Manager. Cisco Bug IDs: CSCve93750, CSCve93762, CSCve93763, CSCvg04127.

What

A vulnerability in the TCL scripting subsystem of Cisco NX-OS System Software could allow an authenticated, local attacker to escape the interactive TCL shell and gain unauthorized access to the underlying operating system of the device. The vulnerability exists due to insufficient input validation of user-supplied files passed to the interactive TCL shell of the affected device. An attacker could exploit this vulnerability to escape the scripting sandbox and execute arbitrary commands on the underlying operating system with the privileges of the authenticated user. To exploit this vulnerability, an attacker must have local access and be authenticated to the targeted device with administrative or tclsh execution privileges. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 5000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, Unified Computing System Manager. Cisco Bug IDs: CSCve93750, CSCve93762, CSCve93763, CSCvg04127.

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 local access may attempt exploitation with elevated privileges. If successful, the issue may execute code or commands in the affected security context.

What

A vulnerability in the TCL scripting subsystem of Cisco NX-OS System Software could allow an authenticated, local attacker to escape the interactive TCL shell and gain unauthorized access to the underlying operating system of the device. The vulnerability exists due to insufficient input validation of user-supplied files passed to the interactive TCL shell of the affected device. An attacker could exploit this vulnerability to escape the scripting sandbox and execute arbitrary commands on the underlying operating system with the privileges of the authenticated user. To exploit this vulnerability, an attacker must have local access and be authenticated to the targeted device with administrative or tclsh execution privileges. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 5000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, Unified Computing System Manager. Cisco Bug IDs: CSCve93750, CSCve93762, CSCve93763, CSCvg04127.

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 local access may attempt exploitation with elevated privileges. If successful, the issue may execute code or commands in the affected security context.

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
local access → Improper Input Validation → execute code or commands in the affected security context
Attack surface
Local
Privileges required
High: elevated access 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:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L

Common Vulnerability Scoring System 3.0: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRHighPrivileges required: The attacker needs elevated or administrative 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.ILowIntegrity impact: A successful attack can cause a limited loss.ALowAvailability impact: A successful attack can cause a limited loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
Remote code executionCWE-20
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 · AV17-181Cisco security updates

al Interface Access Vulnerability CVE References: CVE-2017-12367,CVE-2017-12368,CVE-2017-12367,CVE-2017-12368,CVE-2017-12369,CVE-2017-12370,CVE-2017-12371,CVE-2017-12372,CVE-2017-12367,CVE-2017-12368,CVE-2017-12369,CVE-2017-12370,CVE-2017-12371,CVE-2017-12372,CVE-2017-12343,CVE-2017-12344,CVE-2017-12343,CVE-2017-12344,CVE-2017-12345,CVE-2017-12346,CVE-2017-12347,CVE-2017-12343,CVE-2017-12344,CVE-2017-12345,CVE-2017-12346,CVE-2017-12347,CVE-2017-12359,CVE-2017-12366,CVE-2017-12297,CVE-2017-12365,CVE-2017-12363,CVE-2017-12360,CVE-2017-12348,CVE-2017-12349,CVE-2017-12340,CVE-2017-12364,CVE-2017-12342,CVE-2017-12341,CVE-2017-12339,CVE-2017-12338,CVE-2017-12336,CVE-2017-12335,CVE-2017-12334,CVE-2017-12333,CVE-2017-12351 Suggested Action CCIRC recommends that system administrators test and deploy the vendor-released updates to affected applications accordingly. References: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20171129-webex-players https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20171129-dcnm https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20171129-webex https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20171129-webex5 https://tools.cisco.com/security/center/content/Ci

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2017-010556Cisco NX-OS システムソフトウェアにおける入力確認に関する脆弱性

Cisco NX-OS システムソフトウェアには、入力確認に関する脆弱性が存在します。 ベンダは、本脆弱性を Bug ID CSCve93750、CSCve93762、CSCve93763、および CSCvg04127 として公開しています。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-4807Cisco 제품군 취약점 보안 업데이트 권고

Cisco NX-OS 시스템에서 TCL 스크립트 검증 미흡으로 인해 발생하는 인증우회 취약점(CVE-2017-12336)[19]

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 not verified
Affected
Cisco NX-OS: Cisco NX-OS
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 30 Nov 2017 · Last source change 5 Aug 2024, 18:36 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-2017-3909
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
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-2017-3909 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2017-3909"}
    ENISA EUVD ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: tools.cisco.com/cisco-sa-20171129-nxos5.
    Before
    no authoritative guidance recorded
    After
    vendor advisory: tools.cisco.com/cisco-sa-20171129-nxos5
    tools.cisco.com ↗
  3. SeveritySeverity changed from Unknown to Medium.
    Before
    Unknown
    After
    Medium
    NIST NVD ↗
  4. CVSS scoreCVSS score changed from not recorded to 4.2 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L).
    Before
    not recorded
    After
    4.2 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L)
    NIST NVD ↗
  5. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2017-3909↗Vendor advisory · Cisco CISCO-SA-20171129-NXOS5↗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-2017-12336 · cve.blacktree.nl