How to fix CVE-2026-76504: Cisco Catalyst SD-WAN Manager (exploited in the wild)

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.

• Severity: CRITICAL (CVSS 3.1 9.8, vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
• Weakness: CWE-177.
• NVD published 2026-09-30, status Analyzed.

Anyone running Cisco Catalyst SD-WAN Manager in the version ranges below. Internet-facing instances are the priority.

• cisco catalyst sd-wan manager: up to (not including) 20.9.10.1.
• cisco catalyst sd-wan manager: from 20.12 up to (not including) 20.12.8.2.
• cisco catalyst sd-wan manager: from 20.15 up to (not including) 20.15.6.1.
• cisco catalyst sd-wan manager: from 20.18 up to (not including) 20.18.4.1.
• cisco catalyst sd-wan manager: from 26.1 up to (not including) 26.1.2.1.

Version ranges come from the NVD CPE configuration. Confirm against the vendor advisory before you rely on them.

• Exploited in the wild: added to the CISA Known Exploited Vulnerabilities catalog on 2026-09-30; federal remediation due date 2026-10-03.
• Public proof-of-concept code: 3 GitHub repositories from 3 accounts, the first on 2026-09-30.

• EPSS (probability of exploitation activity in the next 30 days): 1.82%, higher than 79% of all scored CVEs (as of 2026-10-24).
• CVERadar threat level: 65/100 (see methodology).
• Likely ATT&CK techniques: T1190 Exploit Public-Facing Application (inferred).

1. Find every instance. List where Cisco Catalyst SD-WAN Manager runs, including test, DR and forgotten internet-facing systems, and record the installed version.

   show version

2. Upgrade to a fixed release. cisco catalyst sd-wan manager: 20.9.10.1 or later; cisco catalyst sd-wan manager: 20.12.8.2 or later; cisco catalyst sd-wan manager: 20.15.6.1 or later; cisco catalyst sd-wan manager: 20.18.4.1 or later. Get the build from the vendor advisory.
3. If you can't patch today, follow CISA's 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.
4. Verify the fix. Re-run the version check above on every instance and confirm it reports the fixed build (20.9.10.1 or later). Re-scan from outside if the service is exposed.
5. Hunt for signs of earlier compromise. If the system was exposed before you patched, assume it may have been hit and check the items below.
6. Rotate credentials stored on or used by the affected system if you cannot rule out compromise, and keep the logs you reviewed.

Detection hints

• T1190 Exploit Public-Facing Application: Review WAF, reverse-proxy and application logs for unusual requests to Catalyst SD-WAN Manager (odd paths, oversized or encoded payloads, bursts of errors), going back to at least 2026-09-30.

Detection commands are generic starting points, not CVE-specific signatures. Use the indicators from the vendor advisory when it publishes them.

• NVD: CVE-2026-76504 nvd.nist.gov/vuln/detail/CVE-2026-76504
• CVE.org record www.cve.org/CVERecord?id=CVE-2026-76504
• Vendor link from CISA KEV sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/
• CISA KEV catalog www.cisa.gov/known-exploited-vulnerabilities-catalog
• FIRST EPSS (2026-10-24) api.first.org/data/v1/epss?cve=CVE-2026-76504