CVE-2020-16255 in ownCloud
Summary
by MITRE • 01/16/2021
ownCloud (Core) before 10.5 allows XSS in login page 'forgot password.'
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Analysis
by VulDB Data Team • 02/14/2021
The vulnerability CVE-2020-16255 represents a cross-site scripting flaw in ownCloud Core versions prior to 10.5, specifically affecting the login page's 'forgot password' functionality. This issue resides in the web application's input validation mechanisms and demonstrates a classic weakness in user interface sanitization where unfiltered user input is directly rendered without proper encoding or filtering. The vulnerability is categorized under CWE-79 as Cross-Site Scripting, which is a widespread and critical security concern in web applications. Attackers can exploit this flaw by injecting malicious script code into the password reset form, potentially leading to unauthorized access or data exfiltration when victims click on crafted links or visit compromised pages.
The technical implementation of this vulnerability occurs when the application fails to properly sanitize user-supplied input during the password recovery process. When users attempt to reset their passwords through the login page, the system accepts email addresses or usernames without adequate validation or encoding, allowing malicious actors to inject script tags or other malicious code. This flaw typically manifests when the application directly echoes user input into HTML output without proper HTML entity encoding or context-appropriate sanitization. The attack surface is particularly dangerous because it targets the authentication mechanism, which is a critical component of any web application security posture.
The operational impact of CVE-2020-16255 extends beyond simple script injection, as it can enable more sophisticated attacks within the context of the vulnerable ownCloud environment. An attacker could potentially redirect users to malicious sites, steal session cookies, or perform actions on behalf of authenticated users. The vulnerability affects the core authentication flow, making it particularly dangerous for organizations relying on ownCloud for file sharing and collaboration. According to ATT&CK framework, this vulnerability maps to T1531 as "Account Access Removal" and T1071.001 as "Application Layer Protocol: Web Protocols" since it exploits web application vulnerabilities to gain unauthorized access. The potential for credential theft or session hijacking makes this a high-severity issue that could compromise entire user bases within affected organizations.
Mitigation strategies for CVE-2020-16255 require immediate patching of affected ownCloud installations to version 10.5 or later, where the vulnerability has been addressed through proper input sanitization and output encoding. Organizations should implement comprehensive input validation at multiple layers, including client-side and server-side filtering, to prevent malicious code injection. The remediation process should include thorough testing of all user input fields, particularly those in authentication flows, to ensure that all potentially dangerous characters are properly escaped or removed. Security teams should also consider implementing web application firewalls and content security policies to add additional defense-in-depth measures. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other web applications within the organization's infrastructure, as this type of flaw often indicates broader input validation issues that may exist elsewhere in the codebase.