CVE-2009-4093 in Simplog
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in comments.php in Simplog 0.9.3.2, and possibly earlier, allow remote attackers to inject arbitrary web script or HTML via the (1) cname (Name) or (2) email parameters.
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Analysis
by VulDB Data Team • 08/20/2025
The vulnerability identified as CVE-2009-4093 represents a critical cross-site scripting flaw affecting Simplog version 0.9.3.2 and potentially earlier releases. This vulnerability resides within the comments.php script which serves as the primary interface for user comment submission and management. The flaw manifests when the application fails to properly sanitize user input parameters, specifically the cname (Name) and email fields, creating an avenue for malicious actors to inject arbitrary web scripts or HTML content into the application's response. Such vulnerabilities are particularly dangerous as they can be exploited to execute unauthorized code within the context of a victim's browser session, potentially leading to complete compromise of user sessions and data theft.
The technical nature of this vulnerability aligns with CWE-79, which specifically addresses Cross-Site Scripting flaws in software applications. This classification indicates that the application does not adequately validate or escape user-supplied input before incorporating it into dynamically generated web pages. The flaw operates by accepting unfiltered input through the HTTP request parameters and directly embedding them into the HTML output without proper sanitization mechanisms. Attackers can craft malicious payloads that, when processed by the vulnerable application, execute unintended JavaScript code within the browser of unsuspecting users who view the affected comments. The vulnerability demonstrates a classic lack of input validation and output encoding practices that are fundamental to preventing XSS attacks.
The operational impact of this vulnerability extends beyond simple data theft or session hijacking, as it can enable more sophisticated attack vectors including credential harvesting, defacement of web content, and establishment of persistent backdoors within the compromised environment. When users submit comments through the vulnerable form, the malicious scripts embedded in the cname or email fields can execute in the context of other users' browsers who subsequently view these comments. This creates a chain reaction where each affected user becomes a potential vector for further propagation of malicious code. The vulnerability is particularly concerning in web applications where user-generated content is displayed without proper sanitization, as it transforms legitimate user interaction points into attack surfaces.
Mitigation strategies for CVE-2009-4093 must focus on implementing robust input validation and output encoding mechanisms throughout the application's data handling processes. The most effective approach involves sanitizing all user-supplied input parameters before they are processed or stored, ensuring that any potentially dangerous characters or script tags are properly escaped or removed. This aligns with ATT&CK technique T1566.001 which emphasizes the importance of validating and sanitizing user input to prevent injection attacks. Additionally, implementing proper Content Security Policy headers can provide an additional layer of protection by restricting the sources from which scripts can be loaded within the application. Organizations should also consider upgrading to patched versions of Simplog if available, as this vulnerability represents a known flaw that has likely been addressed in subsequent releases. Regular security assessments and input validation testing should be conducted to identify similar vulnerabilities in other application components, as XSS flaws often occur in multiple locations within web applications.