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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 27 Feb 2026.
Catalyst Sd Wan ManagerApplication · Cisco

CVE-2026-20127

CRITICAL · 10.0 CVSS v3.1 Published 2026-02-25
Fix available
A fix is available. Upgrade to 20.9.8.2 / 20.12.5.3 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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. 

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

This is an authentication bypass vulnerability in the peering authentication mechanism of Cisco Catalyst SD-WAN Controller (vSmart), Manager (vManage), and Validator (vBond). The flaw allows an unauthenticated remote attacker to bypass authentication by sending crafted requests, enabling them to log in as a high-privileged non-root user and access NETCONF to manipulate the SD-WAN fabric configuration.

MitigationApply Cisco's security updates for this vulnerability to all affected SD-WAN components (vSmart, vManage, vBond). If patches are unavailable, restrict network access to management interfaces and monitor for unauthorized access attempts.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Catalyst Sd Wan ManagerApplication
Affected:< 20.9.8.2>= 20.11, < 20.12.5.3>= 20.13, < 20.15.4.2>= 20.16, < 20.18.2.1= 20.12.6
Sd Wan Vbond OrchestratorApplication
Affected:< 20.9.8.2>= 20.11, < 20.12.5.3>= 20.13, < 20.15.4.2>= 20.16, < 20.18.2.1= 20.12.6
Sd Wan Vsmart ControllerApplication
Affected:< 20.9.8.2>= 20.11, < 20.12.5.3>= 20.13, < 20.15.4.2>= 20.16, < 20.18.2.1= 20.12.6

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed SD-WAN component versions
    Run the command to display the software version on each SD-WAN device (vBond, vSmart, vManage). Consult your product documentation for the appropriate show command or API endpoint to retrieve the running software version.
    Affected if The installed version falls within any of these ranges: < 20.9.8.2; >= 20.11 and < 20.12.5.3; >= 20.13 and < 20.15.4.2; >= 20.16 and < 20.18.2.1; or exactly version 20.12.6.
  2. Verify if NETCONF is enabled and exposed
    Check the device configuration for NETCONF service enabled status and network accessibility. Review the configuration for 'netconf' or 'xml' service settings, and determine if the NETCONF port (default 830) is listening on external or management interfaces.
    Affected if NETCONF is enabled and reachable from an untrusted network segment on an affected version.
  3. Confirm peering authentication is configured
    Review the SD-WAN peering configuration to determine if the peering authentication mechanism is active between controllers. Look for peering-related settings in the device or controller configuration files.
    Affected if Peering authentication is in use on an affected version.
  4. Review authentication logs for anomalies
    Examine authentication and audit logs on vBond, vSmart, and vManage for successful logins from unexpected sources, high-privileged non-root accounts, or authentication failures followed by successful anonymous access.
    Affected if Log entries show successful authentications as high-privileged users without corresponding legitimate credentials or from unexpected IP addresses.

Your environment is affected if any SD-WAN component (vBond, vSmart, or vManage) runs a version within the affected ranges and has NETCONF accessible with peering authentication enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 20.9.8.2 / 20.12.5.3 / 20.15.4.2 or later
Fixed in 20.9.8.220.12.5.320.15.4.2
Interim mitigation

Apply Cisco's security updates for this vulnerability to all affected SD-WAN components (vSmart, vManage, vBond). If patches are unavailable, restrict network access to management interfaces and monitor for unauthorized access attempts.

Recommended fix High confidence

Cisco Catalyst SD-WAN version 20.18.2.1 or later

  1. 1. Identify the current Cisco Catalyst SD-WAN version by accessing the controller via CLI or the vManage web interface
  2. 2. Determine which version range your current installation falls into: < 20.9.8.2, >= 20.11 and < 20.12.5.3, >= 20.13 and < 20.15.4.2, or >= 20.16 and < 20.18.2.1
  3. 3. Review Cisco Catalyst SD-WAN release notes for version 20.18.2.1 or later to understand any migration requirements
  4. 4. Create a backup of the current SD-WAN configuration before upgrading
  5. 5. Schedule a maintenance window as the upgrade will require brief downtime
  6. 6. Download the appropriate upgrade image from Cisco (requires valid CCO ID and service contract)
  7. 7. Follow Cisco's standard upgrade procedure for SD-WAN components: upgrade vBond first, then vSmart, then vManage
  8. 8. After upgrade, verify that all controllers are running the patched version
Caveat Review Cisco release notes for potential configuration changes between your current version and 20.18.2.1; some older hardware models may have limited upgrade paths

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Catalyst Sd Wan Manager Exploited in the wild — priority engagement
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
36.0 hours of engineering $6,400
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-20127 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data