CVE-2018-0251

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.

Exploit odds

1.8% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2018-04-19 20:29 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 01:30 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.8% in the next 30 days (EPSS).
• Severity: 6.1 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2018-04-19 20:29 UTC

Last modified

2026-06-17 01:30 UTC

Exploit probability

1.8% · EPSS, next 30 days

Weakness

CWE-79 · Cross-site scripting

Record status

Modified

Affected

• Cisco Adaptive Security Appliance Software 9.8\(2.15\)
• Cisco Adaptive Security Appliance Software 9.9\(1\)

Attack profile CVSS 3.0 · 6.1

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2018-0251.md and follow it. Check whether this project is affected by CVE-2018-0251. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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