CVE-2026-76504: Cisco Catalyst SD-WAN Manager

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

Yes, if you run Cisco Catalyst SD-WAN Manager. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-09-30, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-10-03; treat that as the outer limit, not the target.
EPSS 1.8%, percentile 79: FIRST’s model estimates a 1.8% chance of exploitation activity in the next 30 days, higher than 79% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
Editorial verdict: Act now. Cisco SD-WAN Manager CVE-2026-76504: Exploited Auth Bypass — If you run SD-WAN Manager on-prem, upgrade now and check the logs Cisco names; one crafted HTTP request gives an unauthenticated attacker admin over the controller for your whole WAN.

What it is

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.

CISA’s summary

Cisco Catalyst SD-WAN Manager contains a hex encoding vulnerability that could allow an unauthenticated, remote attacker to access an affected system with privileges of the admin user due to improper handling of URI encoding in an HTTP request.

Weakness type: CWE-177.

Product: Cisco Catalyst SD-WAN Manager · Assigned by: cisco · Published: 2026-09-30

Affected and fixed versions

Vendor	Product	Affected versions (per CVE record)
Cisco	Cisco Catalyst SD-WAN Manager	20.1.12, 19.2.1, 18.4.4, 18.4.5, 20.1.1.1, 20.1.1, 19.3.0, 19.2.2, 19.2.099, 18.3.6, 18.3.7, 19.2.0

Severity scores

Scored by	CVSS	Score	Vector
cisco	3.1	9.8 Critical	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

Attack vector: network (remotely reachable)
Attack complexity: low
Privileges required: none (no login)
User interaction: none
Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

CISA KEV: added 2026-09-30; federal due date 2026-10-03. Known ransomware use: Unknown.
CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
CISA SSVC assessment: exploitation active, automatable yes, technical impact total.
FIRST EPSS (model of 2026-10-21): 1.82% probability of exploitation activity in the next 30 days; percentile 79.

Timeline

2026-09-30 — Added to CISA’s Known Exploited Vulnerabilities catalog
2026-09-30 — CVE record published by cisco
2026-09-30 — erroneo.us brief: Cisco SD-WAN Manager CVE-2026-76504: Exploited Auth Bypass
2026-10-02 — CVE record last updated
2026-10-03 — CISA remediation deadline for US federal agencies

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.