CVE-2026-20127

Published Feb 25, 2026

Last updated a month ago

Exploit known CVSS critical 10.0

Network

Zero-day

API

ICS

Tunneling protocol

Bgp

Firmware

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-20127 is an authentication bypass vulnerability affecting Cisco Catalyst SD-WAN Controller (formerly SD-WAN vSmart) and Cisco Catalyst SD-WAN Manager (formerly SD-WAN vManage). This flaw resides within the peering authentication mechanism, which is responsible for establishing trust relationships between SD-WAN components. An unauthenticated, remote attacker can exploit this vulnerability by sending specially crafted requests to an affected system, thereby bypassing the authentication process. Successful exploitation allows the attacker to gain administrative privileges on the affected system, enabling them to log in as a high-privileged, non-root user. From there, the attacker can access NETCONF, which permits the manipulation of network configurations for the entire SD-WAN fabric. This vulnerability has been actively exploited in the wild by sophisticated threat actors, with evidence of malicious activity dating back to 2023.

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. 
Source: psirt@cisco.com
NVD status: Modified
Products: catalyst_sd-wan_manager, sd-wan_vsmart_controller

Risk scores

CVSS 3.1

Type: Primary
Base score: 10
Impact score: 6
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Severity: CRITICAL

Known exploits

Data from CISA

Vulnerability name: Cisco Catalyst SD-WAN Controller and Manager Authentication Bypass Vulnerability
Exploit added on: Feb 25, 2026
Exploit action due: Feb 27, 2026
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.

Weaknesses

psirt@cisco.com: CWE-287
nvd@nist.gov: CWE-287

Hype score: Not currently trending

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "0388BD67-C1AD-4E47-8B1A-22EE1634190E",
            "versionEndExcluding": "20.9.8.2",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "344CA479-F60F-4CD6-83F7-4DB38DF2EAEB",
            "versionEndExcluding": "20.12.5.3",
            "versionStartIncluding": "20.11",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "D284EA84-6C27-4A9C-BDA2-D1C5BF1F2356",
            "versionEndExcluding": "20.15.4.2",
            "versionStartIncluding": "20.13",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "B94E1DC2-5DA5-4238-8040-6D524DDEAA4F",
            "versionEndExcluding": "20.18.2.1",
            "versionStartIncluding": "20.16",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:cisco:catalyst_sd-wan_manager:20.12.6:*:*:*:*:*:*:*",
            "matchCriteriaId": "F5B6E170-73B8-4838-93B4-AD258F3BCA7C",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:cisco:sd-wan_vsmart_controller:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "9C42E29A-D80E-4303-A33E-660099CF78F7",
            "versionEndExcluding": "20.9.8.2",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:cisco:sd-wan_vsmart_controller:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "7B720BE5-BD1D-4BFA-A899-BFB20C7499FC",
            "versionEndExcluding": "20.12.5.3",
            "versionStartIncluding": "20.11",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:cisco:sd-wan_vsmart_controller:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "4BDF8CF0-99BA-461F-99D6-4B1ABE9C2FFF",
            "versionEndExcluding": "20.15.4.2",
            "versionStartIncluding": "20.13",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:cisco:sd-wan_vsmart_controller:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "E709AAB8-3567-49EB-8090-033468743AB4",
            "versionEndExcluding": "20.18.2.1",
            "versionStartIncluding": "20.16",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:cisco:sd-wan_vsmart_controller:20.12.6:*:*:*:*:*:*:*",
            "matchCriteriaId": "3DD7A58E-C95F-48C2-8359-39AFE7FA47BE",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.