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

CVE-2026-20127 is rated critical with a CVSS v3.1 base score of 10.0 and affects Cisco Catalyst SD-WAN Controller and Manager, along with 2 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-02-25, which means exploitation in the wild has been observed.

Vulnerability description

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. 

Severity breakdown

CVSS v3.1 10.0: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: None. No account or prior access is needed.
  • User interaction: None. No action from any user is needed.
  • Scope: Changed. Impact reaches beyond the vulnerable component to other resources.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-287: Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

Affected products

  • Cisco Catalyst SD WAN Manager: before 20.9.8.2; from 20.11 before 20.12.5.3; from 20.13 before 20.15.4.2; from 20.16 before 20.18.2.1; 20.12.6
  • Cisco SD WAN Vbond Orchestrator: before 20.9.8.2; from 20.11 before 20.12.5.3; from 20.13 before 20.15.4.2; from 20.16 before 20.18.2.1; 20.12.6
  • Cisco SD WAN Vsmart Controller: before 20.9.8.2; from 20.11 before 20.12.5.3; from 20.13 before 20.15.4.2; from 20.16 before 20.18.2.1; 20.12.6

References