CVE-2007-2976 in Server
Summary
by MITRE
Centrinity FirstClass 8.3 and earlier, and Server and Internet Services 8.0 and earlier, do not properly handle a URL with a null ("%00") character, which allows remote attackers to conduct cross-site scripting (XSS) attacks. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 03/23/2026
The vulnerability identified as CVE-2007-2976 represents a critical cross-site scripting flaw affecting Centrinity FirstClass versions 8.3 and earlier, along with Server and Internet Services 8.0 and earlier. This security weakness stems from the application's improper handling of URLs containing null character sequences encoded as "%00". The vulnerability falls under the CWE-79 category of Cross-Site Scripting, which is a fundamental web application security issue that allows attackers to inject malicious client-side scripts into web pages viewed by other users. The presence of null characters in URLs creates a parsing inconsistency that bypasses normal input validation mechanisms, enabling attackers to exploit this weakness without requiring any authentication or special privileges.
The technical exploitation of this vulnerability occurs when a malicious actor crafts a specially formatted URL containing a null character sequence and delivers it to unsuspecting users through social engineering tactics, phishing campaigns, or compromised websites. When victims click on such links, the application fails to properly sanitize the URL input, allowing the null character to be processed in a way that enables script execution within the victim's browser context. This flaw specifically targets the URL parsing and validation logic within the FirstClass application, where the null character is not properly escaped or filtered during the request handling process, creating an injection point for malicious payloads.
The operational impact of this vulnerability extends beyond simple XSS attacks, as it provides attackers with a means to execute arbitrary scripts in the context of the victim's browser session. This capability can lead to session hijacking, credential theft, data exfiltration, and the potential for privilege escalation within the application's user context. Attackers could leverage this vulnerability to impersonate legitimate users, access sensitive information, or perform unauthorized actions on behalf of victims. The vulnerability affects the core web application functionality of Centrinity FirstClass, potentially compromising all users who interact with the system through web interfaces, making it particularly dangerous in enterprise environments where such applications are commonly deployed.
Security mitigations for this vulnerability should focus on implementing robust input validation and sanitization mechanisms that properly handle all character sequences including null characters. Organizations should apply the vendor-provided patches or updates that address the URL parsing logic and ensure that all input is properly escaped before processing. Network-level protections such as web application firewalls can provide additional defense-in-depth measures by filtering out suspicious URL patterns containing null characters. The ATT&CK framework categorizes this type of vulnerability under T1203 - Exploitation for Client Execution, highlighting the need for comprehensive application security controls including proper encoding, validation, and secure coding practices. Regular security assessments and input validation testing should be implemented to prevent similar vulnerabilities from emerging in future versions of the application or related systems.