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

TL;DR 📌

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

What happened 🕵️‍♂️

A vulnerability in the Web Authentication feature of Cisco IOS XE Software allows an unauthenticated remote attacker to conduct a reflected cross-site scripting (XSS) attack. This vulnerability arises from improper sanitization of user-supplied input. An attacker could exploit this by persuading a user to click a malicious link, potentially allowing the attacker to steal user cookies from the affected device.

Affected products 🖥️

The vulnerability affects Cisco IOS XE Software when the HTTP or HTTPS features are enabled along with the Web Authentication feature. Specific commands can be used to check if these features are active on your devices.

Fixed software 🔧

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

Workarounds 🧯

There are no workarounds that directly address this vulnerability. However, disabling the HTTP Server feature may eliminate the attack vector. This can be done using the commands no ip http server or no ip http secure-server. Be aware that this may impact other functionalities, such as the Web Management Interface.

Risk in context 🎯

With a CVSS score of 6.1, this vulnerability is rated as Medium severity. The risk is primarily due to the potential for an attacker to exploit the vulnerability through user interaction, as it requires the user to click a malicious link. There is no authentication required for exploitation, making it easier for attackers to target users.

Fast facts ⚡

• Vulnerability Type: Reflected Cross-Site Scripting (XSS)
• CVSS Score: 6.1 (Medium)
• Attack Vector: Remote, unauthenticated
• Exploitation: Proof-of-concept code is available; no known malicious exploitation reported.

For leadership 🧭

Executive summary. A flaw in the web login page of Cisco IOS XE devices could let an attacker trick a user into clicking a malicious link that steals their session cookie for the device’s management interface. It carries a medium severity rating and no workaround beyond disabling the web server, so it should be scheduled into the next patch cycle rather than treated as an emergency.

Why it matters:

• Affects any Cisco IOS XE device with the HTTP or HTTPS server enabled alongside the Web Authentication feature, which is common on devices using the web management interface.
• Exploitation needs no credentials on the attacker’s side, only a user with access to the device’s web login page clicking a crafted link.
• A successful attack can steal the victim’s cookies for the device, which could be used to hijack their authenticated session on the management interface.
• There is no configuration workaround that fixes the flaw directly; the only mitigation is disabling the HTTP/HTTPS server, which removes web-based management entirely.

Now / Next / Later:

• Now: Identify which Cisco IOS XE devices have the HTTP or HTTPS server and Web Authentication feature enabled, using the vendor’s stated check commands.
• Next: Upgrade affected devices to the first fixed release for your software train during the next maintenance window; where patching must wait, disable the HTTP server (no ip http server / no ip http secure-server) if web management can be temporarily done without.
• Later: Review whether device web management interfaces need to be reachable by general users at all, and restrict access to trusted management networks to reduce exposure to this class of web UI flaw in future.