CVE-2014-2856 in CUPS
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in scheduler/client.c in Common Unix Printing System (CUPS) before 1.7.2 allows remote attackers to inject arbitrary web script or HTML via the URL path, related to the is_path_absolute function.
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Analysis
by VulDB Data Team • 05/11/2026
The vulnerability identified as CVE-2014-2856 represents a critical cross-site scripting flaw within the Common Unix Printing System CUPS software version 1.7.1 and earlier. This vulnerability resides in the scheduler/client.c component and specifically targets the is_path_absolute function, which processes URL paths within the printing system's web interface. The flaw enables remote attackers to execute malicious web scripts or HTML code through crafted URL inputs, potentially compromising the security of systems that rely on CUPS for printing services.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the CUPS web interface. When the is_path_absolute function processes URL paths, it fails to properly sanitize user-supplied input, allowing malicious payloads to be embedded within the path parameters. This occurs because the function does not adequately filter or escape special characters that could be interpreted as executable code by web browsers. The vulnerability specifically affects the web-based administrative interface of CUPS, which is commonly accessible to network users and administrators, making it particularly dangerous in enterprise environments where printing services are extensively used.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform various malicious activities including session hijacking, data exfiltration, and privilege escalation within the affected systems. An attacker could potentially inject scripts that steal authentication cookies, redirect users to malicious websites, or manipulate print jobs to execute unauthorized commands. The vulnerability affects systems where CUPS web interface is enabled and accessible, which includes most Unix-like operating systems and Linux distributions that utilize CUPS for printing management. This widespread adoption means that numerous enterprise networks and organizations could be potentially compromised, particularly those with network-accessible print servers.
Organizations affected by this vulnerability should prioritize immediate remediation through patching to CUPS version 1.7.2 or later, which contains the necessary fixes for the XSS vulnerability. System administrators should also implement network segmentation to limit access to CUPS web interfaces and consider disabling the web interface entirely if it is not required for operations. Additional mitigations include implementing web application firewalls that can detect and block suspicious script injection attempts, conducting regular security audits of printing systems, and monitoring for unusual network traffic patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and maps to attack techniques in the MITRE ATT&CK framework under the category of web application attacks, particularly focusing on code injection and credential access vectors. The security community has consistently emphasized the importance of validating all user inputs and properly escaping output to prevent such vulnerabilities, making this a prime example of why input validation should be treated as a fundamental security principle in all software development processes.