The vulnerability in Piranha CMS 12.0 is a stored cross-site scripting (XSS) flaw located in the Text content block feature used within Standard and Standard Archive Pages. This flaw arises because the CMS fails to properly sanitize or encode user-supplied input in the Text block editor accessible through the administrative interface (/manager/pages). An authenticated user with access to the CMS backend can inject arbitrary JavaScript code into the Text block. Upon saving, the malicious script executes immediately in the context of the admin panel and will also execute for any user who subsequently views or previews the affected page. The exploit leverages typical XSS payloads such as an image tag with an onerror event handler, base64-encoded iframe scripts, or HTML5 details toggle events to trigger JavaScript alerts, demonstrating the ability to run arbitrary code. This can lead to theft of session cookies, local and session storage data, and potentially allow attackers to hijack user sessions or perform unauthorized actions within the CMS. The vulnerability requires authenticated access, limiting exploitation to users with at least some level of admin privileges. However, the impact remains significant because it can be used to escalate privileges or compromise other users' sessions. No official patch or fixed version has been released at the time of disclosure, and public exploit code is available, increasing the risk of exploitation. The vulnerability is identified as CVE-2025-57692 and was tested on Ubuntu 22.04 with Chrome browser. The exploit code is provided in plain text format and demonstrates the injection and execution process in detail.

For European organizations using Piranha CMS 12.0, this stored XSS vulnerability poses a moderate risk primarily to the confidentiality and integrity of web application data. Attackers with authenticated access can inject malicious scripts that execute in the browsers of other users, potentially stealing sensitive session cookies and local storage data, leading to session hijacking and unauthorized access. This can result in defacement, data leakage, or further compromise of the CMS environment. The vulnerability could also facilitate lateral movement within the organization if attackers escalate privileges using stolen credentials or session tokens. Given that Piranha CMS is used for managing website content, exploitation could damage brand reputation and trust, especially for organizations with public-facing websites. The requirement for authentication reduces the attack surface but does not eliminate risk, particularly in environments with weak access controls or compromised credentials. The absence of a patch increases exposure time, and the availability of exploit code lowers the barrier for attackers. Organizations in sectors such as government, media, education, and SMEs that rely on Piranha CMS for content management are particularly at risk. Additionally, the vulnerability could be leveraged in targeted attacks against European entities to conduct espionage or disrupt services.

1. Immediately restrict access to the Piranha CMS administrative interface to trusted personnel only, using network segmentation, VPNs, or IP whitelisting. 2. Enforce strong authentication mechanisms, including multi-factor authentication (MFA), to reduce the risk of compromised credentials. 3. Monitor CMS user activity logs for unusual behavior, such as unexpected page creations or edits containing suspicious scripts. 4. Educate CMS administrators and content editors about the risks of injecting untrusted content and the importance of input validation. 5. Implement web application firewalls (WAFs) with custom rules to detect and block common XSS payload patterns targeting the CMS. 6. Regularly back up CMS content and configurations to enable rapid recovery in case of compromise. 7. Follow the Piranha CMS project and security advisories closely for the release of patches or updates addressing this vulnerability, and apply them promptly once available. 8. Consider deploying Content Security Policy (CSP) headers to restrict the execution of inline scripts and reduce the impact of XSS attacks. 9. Conduct internal security assessments and penetration tests focusing on CMS components to identify and remediate similar vulnerabilities proactively.