Cisco Catalyst SD-WAN Manager
CVE-2026-76504
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.
What this means for your business
- It affects Cisco Catalyst SD-WAN Manager. It matters if your company, or a supplier that handles your data, runs it.
- Attackers are already using it. CISA added it to its list of flaws used in real attacks on 30 September 2026.
- An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
What to do
- 1Check whether your company or your suppliers run Cisco Catalyst SD-WAN Manager.
- 2If you do, follow CISA's required action below. No patch reference has been published yet.
- 3Treat it as urgent. US federal agencies must fix it by 3 October 2026. That deadline does not apply to private companies, but it shows how seriously CISA takes it.
- 4Because attackers have used it, check the affected systems for signs of a break-in, not only for the update.
Fastnexa security experts
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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’s wording, unedited. The notes it mentions are in CISA’s catalogue entry.
Scoring
- CVSS
- 9.8 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness
- CWE-177
- Assigned by
- psirt@cisco.com
Dates
- Published
- 2026-09-30
- Last modified
- 2026-09-30
- Added to KEV
- 2026-09-30
- Remediation due
- 2026-10-03
- Sources
- CISA KEV, NVD
Coverage
- Cisco Warns of Attackers Exploiting Critical Authentication Bypass in SD-WAN ManagerThe Hacker News · 2026-09-30
- Cisco warns of new SD-WAN zero-day exploited in attacksBleepingComputer · 2026-09-30