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Cisco NX-OS EUVDEUVD-2026-94449

| CVE-2026-20173 MEDIUM
Allocation of Resources Without Limits or Throttling (CWE-770)
2026-10-07 cisco GHSA-8g9j-7mq6-rw6g
5.8
CVSS 3.1 · Vendor: cisco
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Reach data-plane interface over network
  2. Delivery
    Send high-rate UDP/TCP connection flood
  3. Exploit
    Bypass improper protocol rate limiting
  4. Execution
    Induce control/routing-plane packet loss
  5. Impact
    Temporary denial of service

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Resource allocation limits
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires network-level reachability to a data-plane interface of the affected Cisco NX-OS device and the ability to send a sustained high rate of UDP or TCP connections to it; the root cause is that rate limiting was improperly applied to some protocols. Per the CVSS vector (PR:N/UI:N) no authentication or user interaction is needed. LIMITING FACTORS: impact is availability-only and temporary - routing/control-plane disruption occurs only while the flood is active and clears automatically once traffic stops, with no persistence, data loss, or code execution. Practical risk is further bounded by whether the targeted data-plane interface is reachable from untrusted networks versus trusted internal segments only.

Impact

This is a genuine but comparatively low-urgency issue. The CVSS 5.8 (Medium) vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L describes a network-reachable (AV:N), low-complexity (AC:L), unauthenticated (PR:N) attack with no user interaction, which normally signals easy exploitation. However, every mitigating factor pulls real-world risk down: there is NO confidentiality or integrity impact (C:N/I:N) and only LOW availability impact (A:L), because the description explicitly states the DoS is transient - it 'clears without manual intervention soon after the high rate of traffic is stopped.' The scope change (S:C) reflects that flooding one data-plane interface degrades separate routing/control-plane protocols, which is why this rates above a trivial single-service DoS. No EPSS score was provided in the input, so exploitation probability cannot be quantified. The vulnerability is NOT listed in CISA KEV and no proof-of-concept was referenced, so exploitation status is: no public exploit identified at time of analysis. Net assessment: a real, prioritizable availability bug for operators of exposed Cisco data-center switches, but not an emergency - there is no code execution, no data exposure, and recovery is automatic once traffic stops. Prioritize patching on internet- or untrusted-network-facing NX-OS interfaces; deprioritize for devices reachable only from trusted internal segments.

Exploit ScenarioDerived

An attacker with network reachability to a data-plane interface of an affected Cisco NX-OS device sends a sustained high rate of UDP or TCP connections. Because rate limiting is improperly applied to some protocols, the flood induces packet loss that destabilizes routing and control-plane protocols, producing temporary network disruption. No proof-of-concept was referenced in the input, and the condition self-resolves once the flood ceases.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 07, 2026

Unauthenticated remote attackers can temporarily disrupt Cisco NX-OS devices by flooding a data-plane interface with a high rate of UDP or TCP connections, exhausting resources and causing packet loss that destabilizes routing and control-plane protocols. The denial-of-service condition is availability-only and self-clears once the traffic stops, but the CVSS 3.1 score of 5.8 reflects a scope change and low availability impact. No public exploit code or active exploitation has been identified at time of analysis.

RemediationAI

Vendor-released patch: Cisco has published a security advisory with fixed software versions; consult https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-nscpdos-SnderkC7 to identify the exact upgrade path for your platform and version. As a compensating control, restrict access to data-plane interfaces from untrusted networks using ingress ACLs, and deploy control-plane policing (CoPP) to rate-limit UDP and TCP traffic destined to the device. Be aware that overly aggressive ACLs or CoPP policies may drop legitimate traffic; conversely, if the device's own rate limiting is the flawed component, external ACLs are more reliable than relying on device-internal rate limits. Monitoring for high-rate UDP/TCP bursts to data-plane interfaces can provide early warning, and the temporary nature of the DoS means service resumes automatically once the flood stops.

Affected VersionsENISA

Cisco NX-OS Software 10.3(3)
Cisco NX-OS Software 9.3(4)
Cisco NX-OS Software 8.2(2)
Cisco NX-OS Software 8.3(1)
Cisco NX-OS Software 9.3(14)
Cisco NX-OS Software 7.3(2)D1(3a)
Cisco NX-OS Software 8.4(2)
Cisco NX-OS Software 8.4(6a)
Cisco NX-OS Software 8.3(2)
Cisco NX-OS Software 10.5(5)
Cisco NX-OS Software 7.3(2)D1(1d)
Cisco NX-OS Software 8.4(8)
Cisco NX-OS Software 10.3(7)
Cisco NX-OS Software 10.4(5)
Cisco NX-OS Software 7.3(5)D1(1)
Cisco NX-OS Software 8.4(11)
Cisco NX-OS Software 7.3(9)D1(1)
Cisco NX-OS Software 10.3(8)
Cisco NX-OS Software 10.3(3x)
Cisco NX-OS Software 10.3(5)
Cisco NX-OS Software 10.3(3w)
Cisco NX-OS Software 8.2(6)
Cisco NX-OS Software 10.4(1)
Cisco NX-OS Software 7.3(2)D1(1)
Cisco NX-OS Software 9.2(2t)
Cisco NX-OS Software 9.3(7k)
Cisco NX-OS Software 8.2(8)
Cisco NX-OS Software 10.5(2)
Cisco NX-OS Software 8.2(5)
Cisco NX-OS Software 10.3(3o)
Cisco NX-OS Software 8.2(4)
Cisco NX-OS Software 9.3(15)
Cisco NX-OS Software 10.3(3r)
Cisco NX-OS Software 8.2(3)
Cisco NX-OS Software 9.3(7)
Cisco NX-OS Software 9.2(2v)
Cisco NX-OS Software 10.5(3e)
Cisco NX-OS Software 8.4(1)
Cisco NX-OS Software 8.2(10)
Cisco NX-OS Software 7.3(1)D1(1)
Cisco NX-OS Software 9.3(1)
Cisco NX-OS Software 8.2(7a)
Cisco NX-OS Software 7.3(0)DX(1)
Cisco NX-OS Software 9.2(3y)
Cisco NX-OS Software 10.3(4g)
Cisco NX-OS Software 10.4(3)
Cisco NX-OS Software 9.3(9)
Cisco NX-OS Software 10.3(1)
Cisco NX-OS Software 8.4(4a)
Cisco NX-OS Software 8.2(9)
Cisco NX-OS Software 7.3(7)D1(1)
Cisco NX-OS Software 9.3(10)
Cisco NX-OS Software 8.4(5)
Cisco NX-OS Software 7.3(4)D1(1)
Cisco NX-OS Software 9.3(3)
Cisco NX-OS Software 10.3(3q)
Cisco NX-OS Software 9.3(5w)
Cisco NX-OS Software 9.2(4)
Cisco NX-OS Software 9.3(13)
Cisco NX-OS Software 9.3(12)
Cisco NX-OS Software 9.3(2)
Cisco NX-OS Software 8.4(9)
Cisco NX-OS Software 9.3(11)
Cisco NX-OS Software 9.3(8)
Cisco NX-OS Software 9.2(2)
Cisco NX-OS Software 8.2(1)
Cisco NX-OS Software 10.5(3t)
Cisco NX-OS Software 10.4(4g)
Cisco NX-OS Software 8.1(1)
Cisco NX-OS Software 8.4(7)
Cisco NX-OS Software 7.3(2)D1(2)
Cisco NX-OS Software 9.3(6)
Cisco NX-OS Software 9.3(1z)
Cisco NX-OS Software 10.4(7)
Cisco NX-OS Software 8.4(10)
Cisco NX-OS Software 10.5(3o)
Cisco NX-OS Software 10.5(3s)
Cisco NX-OS Software 8.2(11)
Cisco NX-OS Software 10.3(4)
Cisco NX-OS Software 8.4(4)
Cisco NX-OS Software 8.4(3)
Cisco NX-OS Software 7.3(2)D1(3)
Cisco NX-OS Software 10.4(2)
Cisco NX-OS Software 10.5(3p)
Cisco NX-OS Software 8.4(6)
Cisco NX-OS Software 7.3(6)D1(1)
Cisco NX-OS Software 10.3(6)
Cisco NX-OS Software 7.3(8)D1(1)
Cisco NX-OS Software 7.3(0)D1(1)
Cisco NX-OS Software 10.3(4h)
Cisco NX-OS Software 8.1(2)
Cisco NX-OS Software 10.5(4)
Cisco NX-OS Software 10.3(3p)
Cisco NX-OS Software 9.2(3)
Cisco NX-OS Software 9.3(16)
Cisco NX-OS Software 9.3(7a)
Cisco NX-OS Software 9.2(1)
Cisco NX-OS Software 10.5(1)
Cisco NX-OS Software 10.3(4a)
Cisco NX-OS Software 10.4(6)
Cisco NX-OS Software 10.3(99w)
Cisco NX-OS Software 10.4(4)
Cisco NX-OS Software 8.1(2a)
Cisco NX-OS Software 8.4(12)
Cisco NX-OS Software 10.3(99x)
Cisco NX-OS Software 10.5(3)
Cisco NX-OS Software 9.3(17)
Cisco NX-OS Software 10.3(2)
Cisco NX-OS Software 9.3(5)
Cisco NX-OS Software 7.3(3)D1(1)
Cisco NX-OS Software 8.2(7)

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Cisco NX-OS is the network operating system for Cisco Nexus and MDS switches. This vulnerability stems from improper rate limiting applied to certain protocols, classified as CWE-770 (Allocation of Resources Without Limits or Throttling). An attacker can send sustained high-rate UDP or TCP connections to a data-plane interface, exhausting system resources and indirectly impacting control-plane and routing protocols through packet loss. The scope change (S:C) in the CVSS vector indicates that the vulnerable data-plane component affects other components, though confidentiality and integrity are unaffected. Per the CVSS vector (PR:N/UI:N), no authentication or user interaction is required. The impact is strictly temporary, clearing automatically when the flood ceases.

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Severity by source

Vendor (cisco) PRIMARY 5.8 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
vuln.today AI 5.8 MEDIUM

Remote unauthenticated flood (AV:N/AC:L/PR:N/UI:N); scope changed (S:C) as one interface's flood degrades separate control-plane protocols; only transient availability impact (A:L), no C/I.

3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

Primary rating from Vendor (cisco).

CVSS VectorVendor: cisco

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
Low

DescriptionCVE.org

A vulnerability in Cisco NX-OS Software could allow an unauthenticated, remote attacker to exhaust system resources, causing a denial of service (DoS) condition.

This vulnerability exists because rate limiting was improperly applied to some protocols. An attacker could exploit this vulnerability by sending a high rate of UDP or TCP connections to a data plane interface on an affected device. A successful exploit could allow the attacker to cause instability to various routing and control plane protocols through some packet loss and temporary disruptions, causing a DoS condition. This DoS condition will clear without manual intervention soon after the high rate of traffic is stopped.

Threat Intelligence Overview

EPSS Score
0.4%
Top 71% exploitable
Prevalence
High
Cisco NX-OS powers Nexus switches widely deployed in enterprise and data-center networks
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.4%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact· derived
High
Technical Impact
Partial

Priority Score

29
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +29
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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Out-of-bounds write defects in Cisco NX-OS Software - spanning standalone NX-OS switches, NX-OS System Software running

CVE-2026-20212 CRITICAL
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Remote code execution in the Silicon One integration of Cisco Nexus 9000 Series Switches (Cisco NX-OS Software) lets an

CVE-2026-76453 HIGH
8.8 Oct 07

Improper neutralization of input in Cisco NX-OS software, NX-OS System Software running in ACI mode, and Cisco Unified C

CVE-2026-76458 HIGH
8.6 Oct 07

Remotely triggerable denial-of-service conditions in Cisco NX-OS Software - including NX-OS System Software running in A

CVE-2026-76457 HIGH
8.6 Oct 07

Out-of-bounds read issues in Cisco NX-OS, NX-OS in ACI mode, and managed Cisco UCS software can be triggered by remote,

CVE-2026-76456 HIGH
8.6 Oct 07

Unauthenticated, network-reachable input-validation flaws in Cisco NX-OS Software command processing can disrupt affecte

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