Cisco IOS XE Software Web UI Reflected Cross-Site Scripting Vulnerability

TL;DR 📌

A reflected cross-site scripting (XSS) vulnerability has been identified in the web UI of Cisco IOS XE Software. This flaw could allow unauthenticated remote attackers to execute malicious scripts on affected devices. Cisco has released software updates to address this issue, but no workarounds are available.

What happened 🕵️‍♂️

A vulnerability in the web UI of Cisco IOS XE Software has been discovered, allowing unauthenticated remote attackers to conduct reflected cross-site scripting (XSS) attacks. This vulnerability arises from improper sanitization of user-supplied input, enabling attackers to trick users into clicking malicious links. A successful exploit could allow attackers to steal user cookies from affected devices.

Affected products 🖥️

The vulnerability affects Cisco IOS XE Software when HTTP or HTTPS is enabled along with WebAuth. Devices with the HTTP Server feature enabled are at risk. For detailed information on vulnerable products, refer to the advisory.

Fixed software 🔧

Upgrade to the first fixed release in your train (or later):

Workarounds 🧯

There are no effective workarounds for this vulnerability. Disabling the HTTP Server feature can eliminate the attack vector temporarily. Users can limit exposure by allowing access only from trusted networks.

Risk in context 🎯

With a CVSS score of 6.1, this vulnerability is rated as Medium risk. The exposure is primarily driven by the potential for unauthenticated access via the web UI, which could lead to cookie theft. Immediate remediation is recommended through software updates.

Fast facts ⚡

• Vulnerability Type: Reflected Cross-Site Scripting (XSS)
• CVSS Score: 6.1 (Medium)
• Exploitation Potential: Proof-of-concept code is available, but no known malicious exploitation reported.
• Workarounds: None effective; disabling HTTP Server is a temporary measure.

For leadership 🧭

Executive summary. Devices running Cisco IOS XE with the web-based management interface enabled are exposed to a cross-site scripting flaw that can be used to hijack an administrator’s session cookie via a crafted link. It carries a medium severity rating and should be scheduled into the next routine patch cycle rather than treated as an emergency.

Why it matters:

• The flaw sits in the IOS XE web UI itself, meaning any device with HTTP/HTTPS and WebAuth enabled is a potential target, not just a subset of configurations.
• Exploitation requires no authentication from the attacker’s side, only that an administrator with an active session clicks a crafted link.
• A successful attack yields the victim’s session cookie, which could let an attacker act with that administrator’s privileges on the device’s management interface.
• No effective workaround exists; the only mitigation short of patching is disabling the HTTP Server feature, which removes web UI access entirely.

Now / Next / Later:

• Now: Identify which Cisco IOS XE devices have the HTTP Server feature and WebAuth enabled, and warn administrators managing them not to click unsolicited links while logged into the web UI.
• Next: Upgrade affected devices to the first fixed IOS XE release for their train during the next scheduled maintenance window.
• Later: Restrict web UI access to trusted management networks by default and review whether the HTTP Server feature needs to remain enabled on devices that don’t require it.