CVE-2026-20091 Cisco UCS Manager and FXOS Software Stored Cross-Site Scripting Vulnerability
Authenticated administrators can inject malicious scripts into Cisco UCS Manager and FXOS interfaces, allowing arbitrary code execution or data theft in victim browsers.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-20091?
CVE-2026-20091 is a medium-severity cross-site scripting vulnerability in Cisco Firepower Extensible Operating System (FXOS), published on 25 Feb 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
A vulnerability in the web-based management interface of Cisco FXOS Software and Cisco UCS Manager Software could allow an authenticated, remote attacker to conduct a stored cross-site scripting (XSS) attack against a user of the interface. This vulnerability is due to insufficient validation of user-supplied input by the web-based management interface of an affected system. An attacker could exploit this vulnerability by injecting malicious data into specific pages of the interface. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information. To exploit this vulnerability, the attacker must have valid credentials for a user account with the role of Administrator or AAA Administrator.
Weakness: CWE-79
Which versions are affected by CVE-2026-20091?
How do I fix CVE-2026-20091?
No fix has been published for CVE-2026-20091 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-20091 being exploited?
There is no known exploitation of CVE-2026-20091 in the wild and no public exploit code.
Sources
Also known as GHSA-4pqc-pmx6-jgc9.