---
title: "CVE-2026-20127: Cisco Catalyst SD-WAN Controller and Manager Authentication Bypass Vulnerability"
url: https://erroneo.us/security/cve/CVE-2026-20127/
description: "CVE-2026-20127 (Cisco Catalyst SD-WAN Controller and Manager): Exploited in the wild (CISA KEV). A vulnerability in the peering authentication in Cisco…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-02-25
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-20127"
kev: true
cvss: 10
epss: 0.88476
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Cisco Catalyst SD-WAN Controller and Manager. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-02-25, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-02-27 ; treat that as the outer limit, not the target.
- EPSS 88.5% , percentile 99.8: FIRST’s model estimates a 88.5% chance of exploitation activity in the next 30 days, higher than 99.8% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Editorial verdict: Act now. Cisco SD-WAN CVE-2026-20127: CVSS 10 Bypass, ED 26-03 — If you run on-prem Catalyst SD-WAN control components, upgrade and hunt now: a sophisticated actor has used this bypass for years, and the follow-on SD-WAN bugs CISA keeps adding to KEV show the platform is still being targeted.

## What it is

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. 

## Affected products (CVE record)

- Cisco Cisco Catalyst SD-WAN Manager: 20.1.12, 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

## Severity

- cisco CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: added 2026-02-25; federal due date 2026-02-27. Known ransomware use: Unknown.
- CISA 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.
- CISA SSVC assessment: exploitation active , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 88.48% probability of exploitation activity in the next 30 days; percentile 99.8.

## Sources

- [Listed in CISA KEV notes (sec.cloudapps.cisco.com)](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-rpa-EHchtZk)
- [CVE.org record CVE-2026-20127](https://www.cve.org/CVERecord?id=CVE-2026-20127)
- [NVD entry CVE-2026-20127](https://nvd.nist.gov/vuln/detail/CVE-2026-20127)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20127)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/ed-26-03-mitigate-vulnerabilities-cisco-sd-wan-systems)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/supplemental-direction-ed-26-03-hunt-and-hardening-guidance-cisco-sd-wan-systems)

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Source page: https://erroneo.us/security/cve/CVE-2026-20127/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt