CVE-2026-20127 — Cisco Catalyst Sd-wan Manager

What is CVE-2026-20127?

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.

The record classifies CVE-2026-20127 under weakness class CWE-287. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 4 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 245 days ago.

Severity and exploitation probability

CVSS v3.1 base score: 10 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS (FIRST): 88.4% probability of exploitation in the next 30 days, higher than 99.7% of all scored CVEs
CISA KEV: Listed since 2026-02-25, federal remediation deadline 2026-02-27
Threadlinqs priority: 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
Published: 2026-02-25, last modified 2026-06-16

Is CVE-2026-20127 being exploited?

CISA added CVE-2026-20127 to the Known Exploited Vulnerabilities catalog on 2026-02-25, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-02-27 under BOD 22-01. Weaponised exploit code for CVE-2026-20127 is publicly available. 9 public proof-of-concept repositories are tracked for this identifier. It currently carries a trending score of 48 in the Threadlinqs vulnerability feed.

zerozenxlabs/CVE-2026-20127---Cisco-SD-WAN-Preauth-RCE (github)
sfewer-r7/CVE-2026-20127 (github)
BugFor-Pings/CVE-2026-20127_EXP (github)
yonathanpy/CVE-2026-20127-Cisco-SD-WAN-Preauth-RCE (github)
gigachadusers/cve-2026-20127 (github)
randeepajayasekara/CVE-2026-20127 (github)
abrahamsurf/sdwan-scanner-CVE-2026-20127 (github)
0xBlackash/CVE-2026-20127 (github)

Affected products and versions

Cisco: Catalyst Sd-wan Manager, Catalyst Sd-wan Manager 20.12.6, Sd-wan Vsmart Controller, Sd-wan Vsmart Controller 20.12.6

How to fix CVE-2026-20127

The record marks a vendor fix as available for CVE-2026-20127. Patch reference: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-rpa-EHchtZk. Vendor advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-rpa-EHchtZk. Because CVE-2026-20127 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-02-27. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2026-20127

7 tracked threats in the Threadlinqs corpus reference CVE-2026-20127, either in the campaign’s CVE list or as an indicator on the campaign record.

Cisco Catalyst SD-WAN Manager Zero-Day Exploitation Chain (CVE-2026-20245, CVE-2026-20127, CVE-2026-20182) — CRITICAL · 2026-07-02
Active Exploitation of Cisco Unified Communications Manager WebDialer SSRF (CVE-2026-20230) and Catalyst SD-WAN Manager Root Privilege-Escalation Zero-Day (CVE-2026-20245) — CRITICAL · 2026-07-01
Cisco Catalyst SD-WAN Manager CVE-2026-20245 — Actively Exploited 0-Day: Authenticated File-Upload Command Injection to Root — HIGH · 2026-06-06
CVE-2026-20127: Critical Cisco Catalyst SD-WAN Authentication Bypass Exploited by UAT-8616 Since 2023 (CVSS 10.0) — CRITICAL · 2026-03-16
Cisco Catalyst SD-WAN Manager Active Exploitation — Arbitrary File Overwrite and Credential Exposure (CVE-2026-20122, CVE-2026-20128) — CRITICAL · 2026-03-06
CVE-2026-20127 Cisco Catalyst SD-WAN Zero-Day — UAT-8616 Authentication Bypass Active Exploitation — CRITICAL · 2026-03-02
Cisco Catalyst SD-WAN Zero-Day (CVE-2026-20127) — UAT-8616 Active Exploitation Since 2023, Authentication Bypass to Admin, Critical Infrastructure Targeting — CRITICAL · 2026-02-26

Sources

Enriched from CVE.org, NVD, FIRST EPSS, CISA KEV, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-10-10. This product uses the NVD API but is not endorsed or certified by the NVD.