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CVE-2026-20303: Cisco Catalyst SD-WAN Security Hardening Release - Input Validation Vulnerabilities

• Severity: critical (CVSS 9.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-05 · updated 2026-10-23
• Weakness: CWE-20

Description

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.

Affected products

• Cisco Catalyst SD-WAN Manager: 20.1.12, 19.2.1, 18.4.4, 18.4.5, 20.1.1.1, 20.1.1 (+384)
• Cisco Catalyst SD-WAN Controller: 20.6.4, 20.9.2, 20.3.6, 20.7.2, 20.7.1, 20.5.1 (+139)

References

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-sdwan-faLcR3K
• https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification

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