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CVE-2026-20127

Exploitation: active CVSS 10.0 CRITICAL

CVSS base score: 10.0 (Critical) vendor CNA · v3.1

Score assigned by the vendor's own CVE Numbering Authority (CNA); CISA's Vulnrichment program adds a score only when the CNA omits one.

Cisco Catalyst SD-WAN Controller and Manager Authentication Bypass Vulnerability

Vendor: Cisco   Product: Catalyst SD-WAN Controller and Manager

Description

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.

Lifecycle Timeline

Each milestone comes from a different source, so gaps between them are gaps in what those sources publish, not evidence that nothing happened. EPSS history for this CVE holds 42 points from 2026-02-28, tracked daily from 2026-09-09; earlier points are weekly, which dates a spike to within a week. Peak probability 88.2% on 2026-07-25.

Published Applicability

CVE List v5 (CNA container) 335 affected · 0 fixed · 0 not affected

Check whether a specific version is affected →

What each source publishes about which product versions carry this vulnerability, kept as written rather than merged. Absence here means no source has published applicability data, not that nothing is affected.

Research & News Coverage

DateSourceArticle
2026-05-26 FortiGuard Labs Threat Signal Cisco Catalyst SD-WAN Controller Authentication Bypass Vulnerability

Articles from monitored vendor research blogs and security news feeds that specifically mention this CVE. Coverage begins when feed monitoring started; earlier articles are not indexed.

Detection & Exploitation

Scan
none published
Exploit / Pen Test
Network IDS/IPS
none published
Host / SIEM
none published

Coverage across public collections only: Nuclei and OpenVAS NVT (scan); Snort and Suricata ET Open (network); Sigma and YARA (host/SIEM); Metasploit, Exploit-DB and public GitHub repositories (exploit). Absence here means nothing public was found, not that detection is impossible.
GitHub PoC repositories are collected automatically by PoC-in-GitHub (CC0) and are not vetted: some are fakes and some are malware. Treat them as evidence that code was published, not as code to run.
OpenVAS coverage derives from the Greenbone Community Feed, made available under the Open Database License (ODbL) v1.0; its individual Vulnerability Tests are licensed GNU GPL v2.

CISA Assessment (Vulnrichment / SSVC)

active
yes
total
—
10.0 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CWE-287 — Improper Authentication
2026-02-25

D3FEND Countermeasures

Defensive techniques inferred by MITRE D3FEND from the underlying weakness (CWE-287) — general hardening and detection guidance for this weakness class, not a vendor patch for this specific CVE.

KEV Catalog Status

2026-02-25
2026-02-27
Unknown

Listed By

SourceDateRecord
CISA KEV 2026-02-25 source record →
CISA Vulnrichment 2026-02-25 source record →

Referenced in Advisories

DateAdvisoryIssuer
2026-02-26 2026-002: Multiple Vulnerabilities in Cisco Products CERT-EU
2026-02-25 CISA and Partners Release Guidance for Ongoing Global Exploitation of Cisco SD-WAN Systems CISA
2026-02-25 CSA: Exploitation of SD-WAN Appliances NSA

Weaponization Timeline — Offensive & Testing Tools

No exploit-tool sightings recorded for this CVE.

Evidence tiers are explained on the About page — a merged Metasploit module is far stronger evidence than a distro package mention.

External References