# CVE-2026-20309: Cisco Identity Services Engine reflected XSS in web interface

Source: https://junglewise.ai/threats/cve-2026-20309-cisco-identity-services-engine-reflected-xss-in-web-interface  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-16. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-20309 · Severity: medium · CVSS 6.1 · Published 2026-09-16

Cisco Identity Services Engine (ISE) is a network access control solution that manages user and device authentication. An unauthenticated attacker can craft a malicious link that, when clicked by an ISE administrator, executes arbitrary JavaScript code in their browser session. This could allow theft of session cookies, sensitive configuration data, or modification of ISE policies without the user's knowledge.

Technologies: [Cisco Identity Services Engine](https://junglewise.ai/threats/technologies/identity-services-engine). Vendors: [Cisco](https://junglewise.ai/threats/vendors/cisco).

## Quick answers

**Is CVE-2026-20309 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-20309 being exploited in the wild.

**How severe is CVE-2026-20309?** Medium severity, with a CVSS score of 6.1, published 16 September 2026.

**Which products and versions are affected?** Cisco Identity Services Engine 3.2 and earlier, 3.3 (before Patch 12), 3.4 (before Patch 7), 3.5 (before Patch 4).

**Is there a fix for CVE-2026-20309?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-20309 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-20309?** Check whether you run Cisco Identity Services Engine at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This is a reflected cross-site scripting (XSS) vulnerability (CWE-79) in the web-based management interface of Cisco ISE caused by improper input validation. The vulnerability requires network access to the ISE web interface and social engineering to convince an authenticated user to click a crafted link containing malicious script payload. An attacker can execute arbitrary JavaScript in the browser context of an ISE administrator, potentially stealing session tokens, accessing sensitive browser-based data, or performing unauthorized configuration changes. Patches are available for ISE 3.3 (Patch 12), 3.4 (Patch 7), and 3.5 (Patch 4); users on ISE 3.2 and earlier must upgrade to a newer release.

## Affected products

- Cisco Identity Services Engine 3.2 and earlier, 3.3 (before Patch 12), 3.4 (before Patch 7), 3.5 (before Patch 4)

## Timeline

- 2026-09-16: disclosed

## References

- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-xss-Uz9VWRQ](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-xss-Uz9VWRQ)

## Related threats

- [Cisco Identity Services Engine authorization bypass in management interface](https://junglewise.ai/threats/cve-2026-20183-a-vulnerability-in-the-web-based-management-interface-of-cisco)
- [Cisco Identity Services Engine authorization bypass in certificate enrollment](https://junglewise.ai/threats/cve-2026-20241-a-vulnerability-in-the-authorization-mechanism-of-cisco-identity)
- [A vulnerability in an API of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to bypass authentication.](https://junglewise.ai/threats/cve-2026-76460-cisco-identity-services-engine-incorrect-privileged-api-use)
- [Cisco ISE SQL and HQL injection in APIs](https://junglewise.ai/threats/cve-2026-76451-cisco-ise-sql-and-hql-injection-in-apis)
- [Cisco Identity Services Engine SQL and HQL injection](https://junglewise.ai/threats/cve-2026-76450-cisco-identity-services-engine-sql-and-hql-injection)