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

Exp

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. 

Published: 2026-02-25 Last update: 2026-02-26 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-20127 is rated Critical Active Threat (100/100): CVSS Critical severity, with high exploitation likelihood (EPSS 54.80%, 98th percentile). CISA KEV confirms active exploitation (added 2026-02-25) affecting Cisco / Catalyst SD-WAN Controller and Manager. an authentication bypass (CWE-287) Unauthenticated remote administrative access may be possible. EPSS rose +8.34% over the last day, indicating growing attacker interest. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2026-20127

Name: Cisco Catalyst SD-WAN Controller and Manager Authentication Bypass Vulnerability · CISA KEV detail

Exploit added: 2026-02-25

Action due: 2026-02-27

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.

Exploit prediction scoring system (EPSS) score for CVE-2026-20127

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-29 46.46% 54.80% +8.34%
2 2026-05-27 44.30% 46.46% +2.16%
3 2026-05-22 — 44.30% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-20127

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
10.0 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 6.0 [email protected]
10.0 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 6.0 [email protected]

Weakness enumeration for CVE-2026-20127

Affected software / configurations for CVE-2026-20127

Vendor Product Version Raw CPE
cisco catalyst_sd-wan_manager < 20.9.8.2 cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*
cisco catalyst_sd-wan_manager >= 20.11, < 20.12.5.3 cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*
cisco catalyst_sd-wan_manager >= 20.13, < 20.15.4.2 cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*
cisco catalyst_sd-wan_manager >= 20.16, < 20.18.2.1 cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*
cisco catalyst_sd-wan_manager 20.12.6 cpe:2.3:a:cisco:catalyst_sd-wan_manager:20.12.6:*:*:*:*:*:*:*
cisco sd-wan_vsmart_controller < 20.9.8.2 cpe:2.3:a:cisco:sd-wan_vsmart_controller:*:*:*:*:*:*:*:*
cisco sd-wan_vsmart_controller >= 20.11, < 20.12.5.3 cpe:2.3:a:cisco:sd-wan_vsmart_controller:*:*:*:*:*:*:*:*
cisco sd-wan_vsmart_controller >= 20.13, < 20.15.4.2 cpe:2.3:a:cisco:sd-wan_vsmart_controller:*:*:*:*:*:*:*:*
cisco sd-wan_vsmart_controller >= 20.16, < 20.18.2.1 cpe:2.3:a:cisco:sd-wan_vsmart_controller:*:*:*:*:*:*:*:*
cisco sd-wan_vsmart_controller 20.12.6 cpe:2.3:a:cisco:sd-wan_vsmart_controller:20.12.6:*:*:*:*:*:*:*

References for CVE-2026-20127

cvelogic Threat Intelligence