CVE-2009-1907 in claroline
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in claroline/linker/notfound.php in Claroline 1.8.11 allows remote attackers to inject arbitrary web script or HTML via the Referer HTTP header.
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Analysis
by VulDB Data Team • 03/10/2025
The CVE-2009-1907 vulnerability represents a classic cross-site scripting flaw within the Claroline learning management system version 1.8.11, specifically affecting the linker/notfound.php component. This vulnerability arises from improper input validation and output encoding practices within the application's handling of HTTP headers. The flaw is particularly concerning because it leverages the Referer header, which is automatically included by web browsers during HTTP requests and typically contains the URL of the page that initiated the request. Attackers can exploit this weakness by crafting malicious Referer headers that contain executable JavaScript code or HTML content, which the vulnerable application then processes and reflects back to unsuspecting users.
The technical implementation of this vulnerability stems from the application's failure to properly sanitize or escape user-supplied input from the Referer HTTP header before incorporating it into the web page's output. When Claroline processes the notfound.php script and encounters a missing link reference, it attempts to display the Referer header value as part of an error message or navigation context. This direct injection of unvalidated input creates an environment where malicious scripts can execute within the victim's browser context. The vulnerability is classified as a stored XSS when the malicious content is persisted in the application's database or session storage, though in this case it appears to be a reflected XSS variant since the payload is delivered through the HTTP header and immediately executed.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a range of malicious activities including session hijacking, credential theft, redirection to malicious sites, and data exfiltration. An attacker could craft a Referer header containing a payload that steals cookies or session tokens, potentially allowing them to impersonate legitimate users and gain unauthorized access to the learning management system. The vulnerability affects all users who encounter the notfound.php page when navigating through the Claroline interface, making it particularly dangerous in educational environments where numerous users interact with the platform. According to CWE standards, this vulnerability maps to CWE-79 which specifically addresses cross-site scripting flaws in web applications, and it aligns with ATT&CK technique T1566.001 related to spearphishing through social media.
Mitigation strategies for CVE-2009-1907 should focus on implementing proper input validation and output encoding mechanisms throughout the application's codebase. The most effective immediate fix involves sanitizing all HTTP header inputs, particularly the Referer header, before any output generation occurs. This can be achieved through the implementation of strict input validation routines that filter out or escape potentially malicious characters and patterns. Organizations should also consider implementing Content Security Policy headers to limit the execution of inline scripts and restrict the sources from which scripts can be loaded. Regular security audits and code reviews should be conducted to identify similar vulnerabilities in other components of the Claroline system, while also ensuring that all users are updated to the latest secure versions of the platform. Additionally, network-level protections such as web application firewalls can provide an additional layer of defense by monitoring and blocking suspicious Referer header patterns that may indicate attempted exploitation attempts.