# CVE-2026-76504 — Cisco Catalyst SD-WAN Manager

> As of 2026-09-30, CVE-2026-76504 is a CRITICAL-severity vulnerability in Cisco Catalyst SD-WAN Manager, CVSS v3.1 9.8. Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-76504, most recently “Cisco Catalyst SD-WAN Manager API authentication bypass zero-day (CVE-2026-76504) exploited in the wild”.

**Last updated:** 2026-09-30

## What is CVE-2026-76504?

A vulnerability in the API session-based authentication management of Cisco Catalyst SD-WAN Manager could allow an unauthenticated, remote attacker to access an affected system with privileges of the admin user. This vulnerability is due to improper handling of URI encoding in an HTTP request, which allows the request to bypass an authentication rule that is intended to restrict access to a specific API endpoint. An attacker could exploit this vulnerability by sending a crafted HTTP request to the API of the affected system. A successful exploit could allow the attacker to bypass authentication and gain access to the API as the admin user.

The record classifies CVE-2026-76504 under weakness class [CWE-177](https://cwe.mitre.org/data/definitions/177.html). 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. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 1 day ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 9.8 — CRITICAL (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.9/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-30

## Is CVE-2026-76504 being exploited?

No public exploitation evidence for CVE-2026-76504 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-09-30. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.

## Affected products and versions

- **Cisco**: Catalyst SD-WAN Manager

## How to fix CVE-2026-76504

No vendor patch reference has been recorded for CVE-2026-76504 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-2026-76504

1 tracked threat in the Threadlinqs corpus references CVE-2026-76504, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Cisco Catalyst SD-WAN Manager API authentication bypass zero-day (CVE-2026-76504) exploited in the wild](https://intel.threadlinqs.com/threat/TL-2026-2820) — CRITICAL · 2026-09-30

## Sources

Enriched from CVE.org, GitHub Security Advisories. Last verified by Threadlinqs on 2026-09-30.

**Other references**

- [sec.cloudapps.cisco.com](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-76504
Full detection coverage and IOCs for threats exploiting CVE-2026-76504 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp