CVE-2026-20127 CRITICAL

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

Vendor Cisco
Product Cisco Catalyst SD-WAN Manager
Weakness CWE-287 · Improper authentication
KEV Status Known Exploited
Published February 25, 2026
Last update February 26, 2026
View on NVD All CVEs

CVSS base score

10.0/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

A vulnerability in the peering authentication in Cisco Catalyst SD-WAN Controller, formerly SD-WAN vSmart, and Cisco Catalyst SD-WAN Manager, formerly SD-WAN vManage, 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. 

CISA mandated remediation

02CISA Required Action

Please adhere to CISA’s guidelines to assess exposure and mitigate risks associated with Cisco SD-WAN devices as outlines in CISA’s Emergency Directive 26-03 (URL listed below in Notes) and CISA’s “Hunt & Hardening Guidance for Cisco SD-WAN Devices (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.

Key dates

03Disclosure timeline

February 25, 2026 CVE published
February 26, 2026 Record updated

External resources

04References

NVD — National Vulnerability Database https://nvd.nist.gov/vuln/detail/CVE-2026-20127 CWE — Common Weakness Enumeration https://cwe.mitre.org/data/definitions/287.html CISA KEV Reference https://www.cisa.gov/news-events/directives/ed-26-03-mitigate-… CISA KEV Reference https://www.cisa.gov/news-events/directives/supplemental-direc… CISA KEV Reference https://sec.cloudapps.cisco.com/security/center/content/CiscoS… CISA KEV Reference https://nvd.nist.gov/vuln/detail/CVE-2026-20127