CVE-2015-1376 in Pixabay Images
Summary
by MITRE
pixabay-images.php in the Pixabay Images plugin before 2.4 for WordPress does not validate hostnames, which allows remote authenticated users to write to arbitrary files via an upload URL with a host other than pixabay.com.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 02/20/2025
The vulnerability identified as CVE-2015-1376 resides within the Pixabay Images plugin for WordPress, specifically in the pixabay-images.php file where insufficient hostname validation creates a critical security flaw. This issue affects versions prior to 2.4 of the plugin and represents a classic example of insecure direct object reference vulnerability that can be exploited by authenticated users. The flaw stems from the plugin's failure to properly validate the host portion of URLs used for image uploads, allowing malicious actors to manipulate the upload destination and write files to arbitrary locations on the server.
The technical implementation of this vulnerability exploits the lack of proper input sanitization and validation mechanisms within the plugin's file upload functionality. When users authenticate and attempt to upload images through the plugin interface, the system accepts a URL parameter that specifies the source of the image to be downloaded and stored. Without validating that the hostname portion of this URL matches the expected domain of pixabay.com, attackers can substitute any valid hostname, effectively redirecting the upload process to write files to locations controlled by the malicious actor. This weakness directly maps to CWE-20, which describes improper input validation, and represents a form of path traversal vulnerability that can be leveraged for remote code execution or data manipulation.
The operational impact of this vulnerability extends beyond simple unauthorized file writing, as it provides attackers with a potential foothold for more sophisticated attacks within the WordPress environment. An authenticated user with sufficient privileges can leverage this flaw to upload malicious files, potentially including web shells or other malicious payloads that could compromise the entire WordPress installation. The vulnerability is particularly dangerous because it requires minimal privileges to exploit, as the attacker only needs an authenticated account with upload permissions rather than administrative access. This makes it a prime target for privilege escalation attacks where attackers with low-level user accounts can gain more significant control over the web server.
Mitigation strategies for CVE-2015-1376 should focus on immediate plugin updates to version 2.4 or later, where the hostname validation has been properly implemented. Organizations should also implement network-level restrictions that prevent outbound connections to unauthorized domains, particularly when dealing with file upload functionalities. The implementation of proper input validation and sanitization measures, including strict hostname verification and URL parsing, should be enforced at multiple layers of the application architecture. Additionally, security monitoring should be enhanced to detect unusual file upload patterns and unauthorized file creation activities. This vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and T1059 which covers command and scripting interpreter, as it allows for both privilege escalation and execution of malicious code through the compromised upload functionality. Regular security audits and proper security testing of third-party plugins should be conducted to identify similar validation flaws that could provide similar attack vectors.