title: Reflected XSS when using flashMessages
description: auth0-lock is Auth0's signin solution. Versions of nauth0-lock before and including `11.30.0` are vulnerable to reflected XSS. An attacker can execute arbitrary code when the library's `flashMessage` feature is utilized and user input or data from URL parameters is incorporated into the `flashMessage` or the library's `languageDictionary` feature is utilized and user input or data from URL parameters is incorporated into the `languageDictionary`. The vulnerability is patched in version 11.30.1.
problem types: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
affected:
{
product: lock
vendor: auth0
versions:
status: affected, version: <= 11.30.0
}
metrics:
cvssV3_1: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 8.1
baseSeverity: HIGH
confidentialityImpact: HIGH
integrityImpact: HIGH
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
version: 3.1
]