CVE-2026-1135 is a cross-site scripting (XSS) vulnerability identified in the itsourcecode Society Management System version 1.0. The vulnerability resides in the /admin/activity.php file, where the Title parameter is improperly sanitized, allowing an attacker to inject arbitrary JavaScript code. This flaw can be exploited remotely without requiring authentication, although user interaction is necessary to trigger the malicious script execution, typically by an administrator or user accessing the affected page. The vulnerability can lead to the execution of attacker-controlled scripts in the context of the victim's browser, potentially enabling session hijacking, credential theft, defacement, or redirection to malicious websites. The vulnerability has a CVSS 4.0 base score of 5.3, reflecting medium severity, with an attack vector of network (remote), low attack complexity, no privileges required, and user interaction needed. The exploit code has been publicly disclosed, increasing the likelihood of exploitation attempts. No patches or official fixes have been published yet, and no known active exploitation has been reported. The vulnerability primarily impacts the confidentiality and integrity of user sessions and data within the affected system. The lack of scope change and absence of availability impact reduce the overall severity. The vulnerability affects only version 1.0 of the software, which may limit the affected population depending on adoption rates.

For European organizations using the itsourcecode Society Management System 1.0, this XSS vulnerability poses a risk to the confidentiality and integrity of administrative sessions and data. Attackers could leverage the flaw to hijack admin sessions, manipulate society management data, or conduct phishing attacks by injecting malicious scripts. This could lead to unauthorized access to sensitive member information, disruption of society operations, or reputational damage. Although the vulnerability does not directly impact system availability, the indirect consequences of compromised administrative control could affect operational continuity. The public availability of exploit code increases the risk of opportunistic attacks, especially in environments where the software is exposed to the internet without adequate access controls. European organizations with limited security monitoring or outdated software versions are particularly vulnerable. The impact is more significant in organizations managing sensitive or critical social community data, such as local government societies, housing associations, or social clubs with personal member information.

To mitigate CVE-2026-1135, organizations should implement strict input validation and output encoding on the Title parameter within /admin/activity.php to neutralize malicious scripts. Employing Content Security Policy (CSP) headers can reduce the impact of XSS by restricting script execution sources. Restrict access to the admin interface via network segmentation, VPNs, or IP whitelisting to limit exposure. Monitor logs for suspicious activity related to the vulnerable parameter and user sessions. Since no official patch is currently available, consider applying virtual patching via Web Application Firewalls (WAF) configured to detect and block XSS payloads targeting the Title parameter. Educate administrative users about the risks of clicking untrusted links or opening suspicious content. Regularly update and audit the software to identify and remediate similar vulnerabilities. Finally, plan for upgrading to a patched or newer version once available from the vendor.