CVE-2021-42970 in cxuucms
Summary
by MITRE • 03/29/2022
Cross Site Scripting (XSS) vulnerability exists in cxuucms v3 via the imgurl of /feedback/post/ content parameter.
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Analysis
by VulDB Data Team • 04/01/2022
The CVE-2021-42970 vulnerability represents a critical cross site scripting flaw identified in the cxuucms v3 content management system. This vulnerability specifically manifests through the imgurl parameter within the /feedback/post/ endpoint, creating a pathway for malicious actors to inject arbitrary JavaScript code into the application's response. The vulnerability stems from insufficient input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before rendering it in web pages. This particular attack vector allows threat actors to exploit the system's trust in user input, potentially enabling them to execute malicious scripts in the context of other users' browsers. The affected parameter imgurl within the feedback submission process creates a direct injection point where unvalidated image URLs can contain malicious payloads that execute when rendered by victim browsers. The vulnerability is categorized under CWE-79 which specifically addresses cross site scripting flaws in web applications. This weakness directly maps to attack techniques described in the MITRE ATT&CK framework under T1190 - Exploit Public-Facing Application, where adversaries target web applications to gain unauthorized access or execute malicious code. The vulnerability's impact extends beyond simple script execution as it can enable session hijacking, data theft, and further exploitation of the compromised user's privileges within the CMS environment.
The technical exploitation of this vulnerability requires an attacker to craft a malicious payload that includes JavaScript code within the imgurl parameter when submitting feedback through the vulnerable endpoint. When the CMS processes this input without proper sanitization, the malicious script gets embedded into the page response and executed in the context of other users who view the affected content. The vulnerability's severity is amplified by the fact that it operates within a feedback submission mechanism that is typically accessible to all users, making exploitation relatively straightforward. The lack of proper input validation means that attackers can bypass standard security measures such as content security policies and other defensive mechanisms that rely on predictable input patterns. This vulnerability represents a classic case of insufficient data sanitization where user-provided URLs are directly incorporated into HTML output without appropriate encoding or validation. The attack surface is particularly concerning because feedback forms are often used by legitimate users to share content, making the attack vector more隐蔽 and harder to detect through normal monitoring procedures. The vulnerability's persistence in the system indicates a fundamental flaw in the application's security architecture, specifically in how it handles user input within the content management subsystem.
The operational impact of CVE-2021-42970 extends beyond immediate script execution to encompass potential data breaches, session hijacking, and privilege escalation within the compromised CMS environment. Attackers could leverage this vulnerability to steal user session cookies, enabling them to impersonate legitimate users and access restricted areas of the CMS. The vulnerability also poses risks to the broader system security as it could serve as a foothold for further attacks, including lateral movement within the organization's network infrastructure. Organizations using cxuucms v3 may experience unauthorized access to sensitive content, modification of existing data, or complete compromise of the CMS administrative functions. The vulnerability's exploitation could result in the injection of malicious payloads that redirect users to phishing sites or download additional malware onto victim systems. Security monitoring becomes significantly more challenging as the malicious activity can appear legitimate within the application's normal user interaction patterns. The vulnerability's persistence means that once exploited, attackers can maintain access and continue to execute malicious code over time. The potential for data exfiltration increases substantially as compromised users may unknowingly provide access to confidential information stored within the CMS. Organizations should consider the vulnerability's impact on their overall security posture, particularly if the CMS is integrated with other systems or serves as a gateway to sensitive organizational resources.
Mitigation strategies for CVE-2021-42970 should focus on implementing robust input validation and output encoding mechanisms throughout the cxuucms v3 application. The immediate solution involves sanitizing all user-provided input, particularly URLs and image references, before processing or storing them within the system. Organizations should implement proper HTML encoding of all dynamic content to prevent script execution in browser contexts. Input validation should include strict whitelisting of acceptable URL formats and character sets, rejecting any input that contains potentially malicious patterns. The application should enforce proper content security policies to limit script execution capabilities and prevent unauthorized code injection. Regular security updates and patches should be applied to address known vulnerabilities in the CMS and its dependencies. Organizations should implement web application firewalls to monitor and filter suspicious traffic patterns associated with XSS attacks. Access controls and authentication mechanisms should be strengthened to limit the impact of potential exploitation attempts. Security awareness training for administrators and developers should emphasize the importance of input validation and output encoding in preventing XSS vulnerabilities. Regular penetration testing and vulnerability assessments should be conducted to identify and remediate similar weaknesses throughout the application infrastructure. The implementation of secure coding practices and adherence to established security standards such as OWASP Top Ten guidelines should be mandatory for all development activities involving web applications. Monitoring and logging mechanisms should be enhanced to detect unusual patterns of input submission that may indicate attempted exploitation of XSS vulnerabilities.