CVE-2018-17571 in Vanilla
Summary
by MITRE
Vanilla before 2.6.1 allows XSS via the email field of a profile.
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Analysis
by VulDB Data Team • 03/27/2020
The vulnerability identified as CVE-2018-17571 affects the Vanilla forum software version 2.6.1 and earlier, representing a critical cross-site scripting flaw that specifically targets the email field within user profiles. This issue arises from inadequate input validation and output sanitization mechanisms within the application's profile management functionality. The vulnerability is classified under CWE-79 which defines cross-site scripting as a weakness where an application fails to properly validate or escape user-supplied data before incorporating it into dynamic content served to other users.
The technical exploitation of this vulnerability occurs when an attacker submits malicious script code through the email field of a user profile. When other users view the compromised profile, the malicious script executes in their browsers within the context of the vulnerable application, potentially allowing attackers to steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious websites. The flaw specifically impacts the email field processing, where user input is not properly sanitized before being rendered in HTML contexts, creating an environment where attacker-controlled data can be interpreted as executable code rather than plain text.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it can enable sophisticated attack chains including session hijacking, privilege escalation, and data exfiltration. Attackers can leverage this vulnerability to establish persistent access to user accounts, potentially compromising entire user bases if the forum serves as a primary communication platform for organizations. The vulnerability is particularly dangerous in enterprise environments where forums may contain sensitive business information or serve as critical collaboration platforms. This issue affects the core authentication and user management components of Vanilla, undermining the trust model that users place in the application's security mechanisms.
Mitigation strategies for this vulnerability include immediate patching to Vanilla version 2.6.1 or later, which implements proper input sanitization and output escaping for profile fields. Organizations should also implement comprehensive input validation at multiple layers including client-side and server-side controls, deploy Content Security Policy headers to limit script execution, and conduct regular security audits of user input handling mechanisms. Additionally, implementing proper output encoding for all dynamic content, particularly user-generated data, aligns with ATT&CK technique T1059.005 for command and scripting interpreter execution. The vulnerability demonstrates the critical importance of secure coding practices and proper input validation as outlined in OWASP Top Ten category a03:2021 - Injection, where inadequate sanitization of user inputs leads to various injection-based attacks including XSS. Organizations should also consider implementing web application firewalls and monitoring for suspicious input patterns that may indicate attempted exploitation of similar vulnerabilities.