CVE-2026-20303criticalCWE-20

CVE-2026-20303: critical vulnerability in Cisco Catalyst SD-WAN Controller

Cisco Catalyst SD-WAN Security Hardening Release - Input Validation Vulnerabilities

Published · Updated

Follow this CVE+ Monitor Cisco Catalyst SD-WAN Manager+ Monitor Cisco Catalyst SD-WAN Controller

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

48Vexday Risk Score

No sign of exploitation. It has an official Brazilian government alert and has a public proof of concept.

ssvc Attendcvss 9.9epss 0.5%
from disclosure to weapon22 days
Published on NVDAug 5
1st PoC+22d
Official alert in Brazil

Brazil's federal government published an alert, recommendation or bulletin that cites this vulnerability.

Source: CTIR Gov (GSI) and CISC Gov.br, under the CC BY-ND 3.0 license.
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Catalyst SD-WAN engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20303 are related to improper input validation issues that are grouped under the Common Weakness Enumeration (CWE) CWE-20.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Affected products
Cisco · Cisco Catalyst SD-WAN ControllerCisco · Cisco Catalyst SD-WAN Manager
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
Related CVEs — Cisco Catalyst SD-WAN Controller

In the same product, most dangerous first.

CVE-2026-20182CRITICALCisco Catalyst SD-WAN Controller Authentication Bypass VulnerabilityEPSS 91.8%KEVCVE-2026-20127CRITICALCisco Catalyst SD-WAN Controller Authentication Bypass VulnerabilityEPSS 89.3%KEVCVE-2026-76504CRITICALCisco Catalyst SD-WAN Manager System Account Authorization Bypass VulnerabilityEPSS 38.9%KEVCVE-2026-20133MEDIUMCVE-2026-20133EPSS 31.5%KEVCVE-2026-20262MEDIUMCisco Catalyst SD-WAN Manager Arbitrary File Write VulnerabilityEPSS 29.1%KEVCVE-2026-20122MEDIUMCisco Catalyst SD-WAN Manager Arbitrary File Overwrite VulnerabilityEPSS 25.8%KEV