CVE-2025-12359 is a Server-Side Request Forgery (SSRF) vulnerability identified in the Responsive Lightbox & Gallery plugin for WordPress, specifically in versions up to and including 2.5.3. The vulnerability arises from the 'get_image_size_by_url' function, which fails to properly validate user-supplied URLs when determining image dimensions for gallery items. This lack of validation allows an authenticated attacker with Author-level access or higher to craft requests that cause the server to initiate HTTP requests to arbitrary locations. SSRF vulnerabilities like this can be leveraged to access internal network resources that are otherwise inaccessible externally, potentially exposing sensitive information or enabling further attacks such as internal service manipulation or lateral movement. The vulnerability does not require user interaction beyond authentication, and the CVSS 3.1 base score is 5.4, indicating a medium severity level. The attack vector is network-based with low attack complexity and privileges required at the Author level, but no user interaction is needed. Currently, there are no known exploits in the wild, and no official patches have been linked yet. The vulnerability was published on November 19, 2025, and assigned by Wordfence. Given the widespread use of WordPress and the popularity of the Responsive Lightbox & Gallery plugin, this vulnerability poses a tangible risk to websites that have not updated or mitigated the issue.

For European organizations, this SSRF vulnerability can have significant consequences. Exploitation allows attackers to make arbitrary HTTP requests from the vulnerable web server, potentially accessing internal services such as intranet applications, databases, or cloud metadata endpoints. This can lead to unauthorized disclosure of sensitive information, including internal IP addresses, configuration data, or credentials. Additionally, attackers might manipulate internal services if they are accessible via HTTP, compromising data integrity. While the vulnerability does not directly impact availability, successful exploitation can facilitate further attacks that degrade service or lead to data breaches. Organizations relying on WordPress sites with this plugin, especially those exposing sensitive internal resources or operating in regulated sectors (finance, healthcare, government), face increased risk of compliance violations and reputational damage. The requirement for Author-level authentication limits exposure but does not eliminate risk, as compromised or malicious insiders could exploit this flaw. The absence of known exploits in the wild suggests a window for proactive mitigation before widespread attacks occur.

European organizations should immediately audit their WordPress installations to identify the presence of the Responsive Lightbox & Gallery plugin and its version. Until an official patch is released, practical mitigations include restricting Author-level user privileges to trusted personnel only and monitoring for unusual outbound HTTP requests originating from web servers hosting the plugin. Implementing web application firewalls (WAFs) with custom rules to detect and block suspicious SSRF patterns targeting internal IP ranges can reduce risk. Network segmentation should be enforced to limit the web server's ability to reach sensitive internal services. Additionally, disabling or restricting the plugin's functionality related to external image URL processing can serve as a temporary workaround. Organizations should subscribe to vendor and security mailing lists to promptly apply patches once available. Regular security audits and user access reviews will further reduce the likelihood of exploitation.