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CVE Record

CVE-2026-20127: Cisco Catalyst SD-WAN Controller Authentication Bypass Vulnerability

A vulnerability in the peering authentication in Cisco Catalyst SD-WAN Controller, formerly SD-WAN vSmart, Cisco Catalyst SD-WAN Manager, formerly SD-WAN vManage, and Cisco Catalyst SD-WAN Validator, formerly SD-WAN vBond, could allow an unauthenticated, remote attacker to bypass authentication and obtain administrative privileges on an affected system. This vulnerability exists because the peering authentication mechanism in an affected system is not working properly. An attacker could exploit this vulnerability by sending crafted requests to an affected system. A successful exploit could allow the attacker to log in to an affected Cisco Catalyst SD-WAN Controller as an internal, high-privileged, non-root user account. Using this account, the attacker could access NETCONF, which would then allow the attacker to manipulate network configuration for the SD-WAN fabric. 

CriticalCVSS 10Known exploitedUpdated
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Glexia's TakeHuman reviewedcritical

Security readout for executives and security teams

Plain-English summary

CVE-2026-20127 is a critical Cisco Catalyst SD-WAN authentication bypass. A remote unauthenticated attacker could gain high-privileged internal access and change SD-WAN fabric configuration. CISA lists it in KEV, so active exploitation is supported by a cited government source.

Executive priority

Treat as emergency priority for any Cisco Catalyst SD-WAN environment. It is critical severity, remotely exploitable without credentials, and listed in CISA KEV. The business risk is unauthorized control of SD-WAN configuration, which can disrupt or redirect enterprise connectivity.

Technical view

The flaw is improper peering authentication in Cisco Catalyst SD-WAN Controller, Manager, and Validator. Crafted requests can bypass authentication and log in as an internal high-privileged non-root user. That access can reach NETCONF and manipulate SD-WAN network configuration. CVSS is 10.0: network-reachable, low complexity, no privileges, no user interaction.

Likely exposure

Organizations running affected Cisco Catalyst SD-WAN Controller, Manager, or Validator deployments are exposed, especially where SD-WAN control-plane services are reachable from untrusted networks. The provided affected-version data is extensive but incomplete for all named components, so confirm against Cisco’s advisory and local software inventory.

Exploitation context

CISA KEV listing indicates known exploitation. The source bundle does not provide exploit details, actor attribution, or exploitation scale. Because exploitation can grant administrative-level control over SD-WAN configuration, compromise could affect routing, segmentation, availability, and traffic handling across the fabric.

Researcher notes

The bundle supports CWE-287, CVSS 10.0, unauthenticated remote access, and KEV status. It does not include fixed-version details or Cisco’s full product matrix beyond the supplied affected Manager versions. Avoid assuming exploit mechanics beyond crafted requests and authentication bypass described by Cisco/CVE sources.

Mitigation direction

  • Check Cisco’s advisory for fixed releases and component-specific remediation guidance.
  • Prioritize upgrades or vendor-directed mitigations for all exposed SD-WAN controllers, managers, and validators.
  • Restrict management and control-plane access to trusted networks only.
  • Review SD-WAN administrative accounts and configuration integrity after remediation.
  • Follow CISA KEV remediation timelines if applicable to your organization.

Validation and detection

  • Inventory Cisco Catalyst SD-WAN Controller, Manager, and Validator versions.
  • Compare installed versions against Cisco’s advisory and affected-version data.
  • Confirm whether devices are reachable from untrusted networks.
  • Review authentication, NETCONF, and configuration-change logs for suspicious activity.
  • Verify remediation by confirming upgraded or mitigated versions in production.
Prepared
Reviewed
Confidence
high
Sources
4

Public sources used

Michael Williams reviewed this cited source version on .

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-287: Credential and account abuse lookup

Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-20127 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
10 (3.1)
Known Exploited
Yes
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
4Timeline events
1ADP providers
3Source links

CISA KEV status

Status
Known exploited
Source
CISA-ADP
Date added
KEV reference

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: activeAutomatable: yesTechnical Impact: total

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
10CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H3.96cisco

Vulnerability scoring details

Base CVSS 3.1 score

10Critical
CVSS 3.1 vector shape for CVE-2026-20127Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. Added to KEVCISA-ADP

    CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvcother:kev

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
CiscoCisco Catalyst SD-WAN Manager20.1.12, 19.2.1, 18.4.4, 18.4.5, 20.1.1.1, 20.1.1, 19.3.0, 19.2.2, 19.2.099, 18.3.6, 18.3.7, 19.2.0, 18.3.8, 19.0.0, 19.1.0, 18.4.302, 18.4.303, 19.2.097, 19.2.098, 17.2.10, 18.3.6.1, 19.0.1a, 18.2.0, 18.4.3, 18.4.1, 17.2.8, 18.3.3.1, 18.4.0, 18.3.1, 17.2.6, 17.2.9, 18.3.4, 17.2.5, 18.3.1.1, 18.3.5, 18.4.0.1, 18.3.3, 17.2.7, 17.2.4, 18.3.0, 19.2.3, 18.4.501_ES, 20.3.1, 20.1.2, 19.2.929, 19.2.31, 20.3.2, 19.2.32, 20.3.2_925, 20.3.2.1, 20.3.2.1_927, 18.4.6, 20.1.2_937, 20.4.1, 20.3.2_928, 20.3.2_929, 20.4.1.0.1, 20.3.2.1_930, 19.2.4, 20.5.0.1.1, 20.4.1.1, 20.3.3, 19.2.4.0.1, 20.3.2_937, 20.3.3.1, 20.5.1, 20.1.3, 20.3.3.0.4, 20.3.3.1.2, 20.3.3.1.1, 20.4.1.2, 20.3.3.0.2, 20.4.1.1.5, 20.4.1.0.01, 20.4.1.0.02, 20.3.3.1.7, 20.3.3.1.5, 20.5.1.0.1, 20.3.3.1.10, 20.3.3.0.8, 20.4.2, 20.4.2.0.1, 20.3.4, 20.3.3.0.14, 19.2.4.0.8, 19.2.4.0.9, 20.3.4.0.1, 20.3.2.0.5, 20.6.1, 20.5.1.0.2, 20.3.3.0.17, 20.6.1.1, 20.6.0.18.3, 20.3.2.0.6, 20.6.0.18.4, 20.4.2.0.2, 20.3.3.0.16, 20.3.4.0.5, 20.6.1.0.1, 20.3.4.0.6, 20.6.2, 20.7.1EFT2, 20.3.4.0.9, 20.3.4.0.11, 20.4.2.0.4, 20.3.3.0.18, 20.7.1, 20.6.2.1, 20.3.4.1, 20.5.1.1, 20.4.2.1, 20.4.2.1.1, 20.3.4.1.1, 20.3.813, 20.3.4.0.19, 20.4.2.2.1, 20.5.1.2, 20.3.4.2, 20.3.814, 20.4.2.2, 20.6.2.2, 20.3.4.2.1, 20.7.1.1, 20.3.4.1.2, 20.6.2.2.2, 20.3.4.0.20, 20.6.2.2.3, 20.4.2.2.2, 20.3.5, 20.6.2.0.4, 20.4.2.2.3, 20.3.4.0.24, 20.6.2.2.7, 20.6.3, 20.3.4.2.2, 20.4.2.2.4, 20.7.1.0.2, 20.8.1, 20.3.5.0.8, 20.3.5.0.9, 20.4.2.2.8, 20.3.5.0.7, 20.6.3.0.7, 20.6.3.0.5, 20.6.3.0.10, 20.6.3.0.2, 20.7.2, 20.9.1EFT2, 20.6.3.0.11, 20.6.3.1, 20.6.3.0.14, 20.6.4, 20.9.1, 20.6.3.0.19, 20.6.3.0.18, 20.3.6, 20.9.1.1, 20.6.3.0.23, 20.6.4.0.4, 20.6.3.0.25, 20.6.5, 20.6.3.0.27, 20.9.2, 20.9.2.1, 20.6.3.0.29, 20.6.3.0.31, 20.6.3.0.32, 20.10.1, 20.6.3.0.33, 20.9.2.0.01, 20.9.1_LI_Images, 20.10.1_LI_Images, 20.9.2_LI_Images, 20.3.7, 20.9.3, 20.6.5.1, 20.11.1, 20.11.1_LI_Images, 20.9.3_LI_ Images, 20.6.3.1.1, 20.9.3.0.2, 20.6.5.1.2, 20.9.3.0.3, 20.4.2.3, 20.6.3.2, 20.6.4.1, 20.6.3.0.38, 20.6.3.0.39, 20.3.5.1, 20.3.4.3, 20.9.3.1, 20.3.3.2, 20.6.5.2, 20.3.7.1, 20.10.1.1, 20.6.5.2.1, 20.3.4.0.25, 20.6.2.2.4, 20.6.1.2, 20.11.1.1, 20.9.3.0.5, 20.3.4.0.26, 20.6.5.1.3, 20.6.3.0.40, 20.1.3.1, 20.9.2.2, 20.6.5.2.3, 20.6.5.1.4, 20.6.5.3, 20.6.3.0.41, 20.9.3.0.7, 20.6.5.1.5, 20.9.3.0.4, 20.6.4.0.19, 20.6.5.1.6, 20.9.3.0.8, 20.6.3.3, 20.3.7.2, 20.6.5.4, 20.6.5.1.7, 20.9.3.0.12, 20.6.4.2, 20.6.5.5, 20.9.3.2, 20.11.1.2, 20.6.3.4, 20.10.1.2, 20.6.5.1.9, 20.9.3.0.16, 20.6.3.0.45, 20.6.5.1.10, 20.9.3.0.17, 20.6.5.2.4, 20.6.4.0.21, 20.9.3.0.18, 20.6.3.0.46, 20.6.3.0.47, 20.9.2.3, 20.9.3.2_LI_Images, 20.9.3.0.21, 20.9.3.0.20, 20.9.4_LI_Images, 20.9.4, 20.6.5.1.11, 20.12.1, 20.12.1_LI_Images, 20.6.5.1.13, 20.9.3.0.23, 20.6.5.2.8, 20.9.4.1, 20.9.4.1_LI_Images, 20.9.3.0.25, 20.9.3.0.24, 20.6.5.1.14, 20.3.8, 20.6.6, 20.9.3.0.26, 20.6.3.0.51, 20.9.3.0.29, 20.12.2, 20.12.2_LI_Images, 20.6.6.0.1, 20.13.1_LI_Images, 20.9.4.0.4, 20.13.1, 20.9.4.1.1, 20.9.5, 20.9.5_LI_Images, 20.12.3_LI_Images, 20.12.3, 20.9.4.1.3, 20.6.7, 20.9.5.1, 20.9.5.1_LI_Images, 20.9.4.1.6, 20.14.1, 20.14.1_LI_Images, 20.9.5.2, 20.9.5.2.1, 20.9.5.2_LI_Images, 20.12.3.1, 20.12.4, 20.15.1_LI_Images, 20.15.1, 20.9.5.1.4, 20.9.5.2.7, 20.9.5.2.13, 20.9.6, 20.9.6_LI_Images, 20.9.5.2.14, 20.6.8, 20.12.4.0.03, 20.16.1, 20.16.1_LI_Images, 20.12.4_LI_Images, 20.9.5.2.16, 20.12.4.0.4, 20.12.401, 20.9.5.3, 20.9.5.3_LI_Images, 20.12.4.1_LI_Images, 20.12.4.1, 20.9.5.2.21, 20.9.6.0.3, 20.12.4.0.6, 20.15.2_LI_Images, 20.15.2, 20.12.4_Monthly_ES5, 20.12.5, 20.12.5_LI_Images, 20.9.7_LI _Images, 20.9.7, 20.15.3, 20.15.3_ LI _Images, 20.12.501, 20.12.5.1_LI_Images, 20.12.5.1, 20.12.5.2_LI_Images, 20.12.5.2, 20.15.3.1, 20.15.4_LI_Images, 20.15.4, 20.9.7.1_LI _Images, 20.9.7.1, 20.18.1, 20.18.1_LI_Images, 20.12.6_LI_Images, 20.12.6, 20.12.5.1.01, 20.9.8, 20.9.8_LI_Images, 20.18.2, 20.15.4.1_LI_Images, 20.15.4.1, 20.18.2_LI_Imagesunknown
Weakness

CWE details

CWE-287

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-287 · source CWE mapping

Improper Authentication

Improper Authentication represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs