CVE-2018-0251: A vulnerability in the Web Server Authentication Required screen of the Clientless Secure Sockets Layer (SSL) VPN portal of Cisco Adaptive Security Ap...

Description

A vulnerability in the Web Server Authentication Required screen of the Clientless Secure Sockets Layer (SSL) VPN portal of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a user of that portal on an affected device. The vulnerability is due to insufficient validation of user-supplied input by the web-based interface of an affected device. An attacker could exploit this vulnerability by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the portal or allow the attacker to access sensitive browser-based information. This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco ASA Software: 3000 Series Industrial Security Appliances, Adaptive Security Virtual Appliance (ASAv), ASA 5500 Series Adaptive Security Appliances, ASA 5500-X Series Next-Generation Firewalls, ASA Services Module for Cisco Catalyst 6500 Series Switches, ASA Services Module for Cisco 7600 Series Routers. Cisco Bug IDs: CSCvh20742.

Metrics

EPSS Probability

1.89%

76.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Cisco	Adaptive Security Appliance Software	9.8\(2.15\)
Cisco	Adaptive Security Appliance Software	9.9\(1\)

References

http://www.securityfocus.com/bid/103926Third Party Advisory, VDB Entry
http://www.securitytracker.com/id/1040714Third Party Advisory, VDB Entry
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-asawvpn2Vendor Advisory
http://www.securityfocus.com/bid/103926Third Party Advisory, VDB Entry
http://www.securitytracker.com/id/1040714Third Party Advisory, VDB Entry
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-asawvpn2Vendor Advisory

Timeline

Published: Apr 19, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-0251?

A vulnerability in the Web Server Authentication Required screen of the Clientless Secure Sockets Layer (SSL) VPN portal of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a user of that portal on an affected device. The vulnerability is due to insufficient validation of user-supplied input by the web-based interface of an affected device. An attacker could exploit this vulnerability by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the portal or allow the attacker to access sensitive browser-based information. This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco ASA Software: 3000 Series Industrial Security Appliances, Adaptive Security Virtual Appliance (ASAv), ASA 5500 Series Adaptive Security Appliances, ASA 5500-X Series Next-Generation Firewalls, ASA Services Module for Cisco Catalyst 6500 Series Switches, ASA Services Module for Cisco 7600 Series Routers. Cisco Bug IDs: CSCvh20742.

How severe is CVE-2018-0251?

Severity scoring for CVE-2018-0251 is pending analysis. The EPSS model estimates a 1.89% probability of exploitation in the next 30 days.

How do I fix CVE-2018-0251?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.