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

[event] Cisco Catalyst SD-WAN Controller, formerly SD-WAN vSmart, and Cisco Catalyst SD-WAN Manager, formerly SD-WAN vManage, contain an authentication bypass vulnerability 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.

> AFFECTED SOFTWARE

> MITIGATION

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.

Due Date: 2026-02-27

> REFERENCES

• [1] https://www.cisa.gov/news-events/directives/ed-26-03-mitigate-vulnerabilities-ci...
• [2] https://www.cisa.gov/news-events/directives/supplemental-direction-ed-26-03-hunt...
• [3] https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/ci...
• [4] https://nvd.nist.gov/vuln/detail/CVE-2026-20127