What is CVE-2026-20303?
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.
The record classifies CVE-2026-20303 under weakness class CWE-20. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 66 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 9.9 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - EPSS (FIRST)
- 0.4% probability of exploitation in the next 30 days, higher than 39.9% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 8.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-08-05, last modified 2026-08-14
Is CVE-2026-20303 being exploited?
Weaponised exploit code for CVE-2026-20303 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 36 in the Threadlinqs vulnerability feed.
- HORKimhab/Cisco-CVE-2026-20303-More (github)
Affected products and versions
- Cisco: Catalyst SD-WAN Controller, Catalyst SD-WAN Manager
How to fix CVE-2026-20303
No vendor patch reference has been recorded for CVE-2026-20303 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-20303
1 tracked threat in the Threadlinqs corpus references CVE-2026-20303, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, FIRST EPSS, public proof-of-concept repositories. Last verified by Threadlinqs on .