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Full vulnerability report · 2019
CVE-2019-12656High confidence

Cisco IOx Application Environment Denial of Service Vulnerability

Cisco · Cisco Industrial Routers Operating System Software

Official source article: Cisco CISCO-SA-20190925-IOX ↗. Check the applicable product and release in the original source.

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

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 1.82% for the current model date.

Compensating controls

  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Cisco Cisco Industrial Routers Operating System Software 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: 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.

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-2019-4247

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 actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
01

What, why and how

A vulnerability in the IOx application environment of multiple Cisco platforms could allow an unauthenticated, remote attacker to cause the IOx web server to stop processing HTTPS requests, resulting in a denial of service (DoS) condition. The vulnerability is due to a Transport Layer Security (TLS) implementation issue. An attacker could exploit this vulnerability by sending crafted TLS packets to the IOx web server on an affected device. A successful exploit could allow the attacker to cause the IOx web server to stop processing HTTPS requests, resulting in a DoS condition.

What

A vulnerability in the IOx application environment of multiple Cisco platforms could allow an unauthenticated, remote attacker to cause the IOx web server to stop processing HTTPS requests, resulting in a denial of service (DoS) condition. The vulnerability is due to a Transport Layer Security (TLS) implementation issue. An attacker could exploit this vulnerability by sending crafted TLS packets to the IOx web server on an affected device. A successful exploit could allow the attacker to cause the IOx web server to stop processing HTTPS requests, resulting in a DoS condition.

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 disrupt the affected service.

What

A vulnerability in the IOx application environment of multiple Cisco platforms could allow an unauthenticated, remote attacker to cause the IOx web server to stop processing HTTPS requests, resulting in a denial of service (DoS) condition. The vulnerability is due to a Transport Layer Security (TLS) implementation issue. An attacker could exploit this vulnerability by sending crafted TLS packets to the IOx web server on an affected device. A successful exploit could allow the attacker to cause the IOx web server to stop processing HTTPS requests, resulting in a DoS condition.

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 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.
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
a network path → Improper Input Validation → disrupt the affected service
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:3.1/AV:N/AC:L/PR:N/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.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.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.
NetworkUnauthenticatedDenial of serviceCWE-20
A

Official authority intelligence

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

CERT-FR · French · CERTFR-2019-AVI-468Multiples vulnérabilités dans les produits Cisco

De multiples vulnérabilités ont été découvertes dans les produits Cisco. Elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, un déni de service à distance et un contournement de la politique de sécurité.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2019-010189複数の Cisco プラットフォームにおける脆弱性

複数の Cisco プラットフォームには、不特定の脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5050Cisco 제품 취약점 보안 업데이트 권고

-2019-12646, 12655) [1][9] o Cisco Catalyst 4000 시리즈 스위치에서 부적절한 자원할당으로 인해 발생하는 서비스 거부 취약점(CVE-2019-12652) [2] o Cisco IOS Software의 IOx 어플리케이션에서 잘못된 접근통제로 인해 비허가된 사용자가 시스템에 접근 가능한 취약점(CVE-2019-12648) [3] o Cisco IOS XE 소프트웨어의 웹 인터페이스에서 발생하는 커맨드 인젝션 취약점(CVE-2019-12650, 12651) [4] o Cisco IOS 및 IOS XE 소프트웨어의 SIP(Session Initiation 프로토콜)에서 내부 데이터 구조에 대한 미흡한 위생처리로 인해 발생하는 서비스거부 취약점(CVE-2019-12654) [5] o Cisco IOS XE 소프트웨어에서 Raw Socket Transport 페이로드를 부적절하게 파싱하여 발생하는 서비스거부 취약점(CVE-2019-12653) [6] o Cisco IOS XE 소프트웨어에서 파일시스템 자원에 대한 관리가 미흡하여 발생하는 서비스거부 취약점(CVE-2019-12658) [7] o Cisco IOx 어플리케이션에서 TLS(Transport Layer Security) 문제로 인해 발생하는 서비스거부 취약점(CVE-2019-12656) [8] o Cisco IOS XE 소프트웨어에서 IPv6 패킷에 대한 처리가 미흡하여 발생하는 서비스거부 취약점(CVE-2019-12657) [10] o Cisco IOS 및 IOS XE 소프트웨어에서 널 포인터 역참조로 인해 발생하는 서비스거부 취약점(CVE-2019-12647) [11] ##### □ 영향을 받는 제품 o Cisco IOS XE 소프트웨어 - Cisco 1100, 4200, 4300 Integrated Services Routers (ISRs) - Cisco Cloud Services Router (CSR) 1000V Series - Cisco Enterprise Network Compute System (ENCS) - Cisco Integrated Services Virtual Router (ISRv) - 16.9버전을 구동중인 Cisco ASR 900 Series routers o Cisco Catalyst 4000 시리즈 스위치 - Cisco Catalyst 4500 Supervisor Engine 6-E - Cisco Catalyst 4500 Supervisor Engine 6L-E - Cisco Catalyst 4900M Switch - Cisco Catalyst 4948E Ethernet Switch - Cisc

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 Industrial Routers Operating System Software: unspecified < n/a
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. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 25 Sept 2019 · Last source change 19 Nov 2024, 18:55 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-2019-4247
Product sourceCNA
Remediation sourceCVE/CNA references
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. ENISA EUVD mappingEUVD-2019-4247 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2019-4247"}
    ENISA EUVD ↗
  2. CVSS scoreCVSS version changed from 3.0 to 3.1; the displayed base score remains 7.5.
    Before
    7.5 (CVSS 3.0 · CNA · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
    After
    7.5 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
    NIST NVD ↗
  3. 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-2019-4247↗CVE authority or vendor reference · Cisco CISCO-SA-20190925-IOX↗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-2019-12656 · cve.blacktree.nl