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

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 25 Feb 2026, the same day the CVE record was published.

How likely is exploitation in the next 30 days?

89.3%

EPSS score, percentile 99.8 of all scored records

How severe?

10.0 Critical

CVSS v3.1 base score, given by the CNA

What should I do?

Required action (CISA), due 27 Feb 2026: 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.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected: 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

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 27 February 2026.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

• https://www.cisa.gov/news-events/directives/ed-26-03-mitigate-vulnerabilities-cisco-sd-wan-systems
• https://www.cisa.gov/news-events/directives/supplemental-direction-ed-26-03-hunt-and-hardening-guidance-cisco-sd-wan-systems
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-rpa-EHchtZk
• https://nvd.nist.gov/vuln/detail/CVE-2026-20127

Affected products and versions

As listed in the CVE record.

Versions not listed are: unknown.

And 323 more version entries in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

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.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2026-20127 to its Known Exploited Vulnerabilities (KEV) catalog on 25 Feb 2026.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 27 Feb 2026.
• The CVE record was published on 25 Feb 2026, the same day it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 10.0 (Critical), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 89.3% (percentile 99.8), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

Cisco Catalyst SD-WAN Controller Authentication Bypass Vulnerability

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: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-287

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

References

• cisco-sa-sdwan-rpa-EHchtZk

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