Description: If GoAccess is configured to generate HTML reports, and the log data processed contains malicious JavaScript code (either injected or legitimately present but unsanitized), this code can be included in the generated HTML report without proper sanitization by GoAccess. When a user views this report in a web browser, the malicious JavaScript could be executed. This is a vulnerability directly within GoAccess's HTML report generation functionality if it fails to sanitize log data properly. Impact: * Account Takeover: Attackers can steal user session cookies or credentials of users viewing the GoAccess HTML reports. * Data Theft: Malicious scripts can access sensitive data within the browser of users viewing the reports, or potentially on their system. * Website Defacement: The attacker can modify the content of the HTML report as displayed in the user's browser, potentially misleading users or causing reputational damage. * Redirection to Malicious Sites: Users viewing the report could be redirected to attacker-controlled websites, potentially leading to further compromise. GoAccess Component Affected: HTML Report Generation Module Risk Severity: High Mitigation Strategies: * Strict Output Sanitization (GoAccess Development): The primary mitigation relies on GoAccess itself properly sanitizing all user-controlled data (derived from logs) before including it in HTML reports. Ensure you are using a reasonably recent and actively maintained version of GoAccess, and check for security advisories related to XSS. * Content Security Policy (CSP): If your application serves the GoAccess HTML reports, implement a strong Content Security Policy to mitigate the impact of potential XSS vulnerabilities. CSP can restrict the sources from which the browser can load resources and execute scripts, limiting the damage an XSS attack can cause. * Avoid Serving HTML Reports Directly to Untrusted Users: Restrict access to GoAccess HTML reports to trusted users only. If possible, consider using alternative output formats like JSON for programmatic consumption, especially when dealing with potentially untrusted environments or users. * Input Sanitization (Pre-GoAccess - Defense in Depth): As a secondary measure, consider sanitizing log data before it is processed by GoAccess to remove or escape potentially malicious HTML or JavaScript code. This adds a layer of defense, although the primary responsibility for XSS prevention in HTML reports lies with GoAccess's output sanitization.