CVE-2026-1135 is a cross-site scripting (XSS) vulnerability identified in the itsourcecode Society Management System version 1.0. The vulnerability exists in the /admin/activity.php file, where the 'Title' parameter is improperly sanitized, allowing an attacker to inject malicious JavaScript code. This flaw can be exploited remotely without requiring authentication, though it requires user interaction, such as an administrator clicking a malicious link or visiting a crafted page. The vulnerability is classified as reflected XSS, where the injected script executes in the context of the victim's browser, potentially leading to session hijacking, credential theft, or unauthorized actions within the admin panel. The CVSS 4.0 score is 5.3 (medium severity), reflecting the network attack vector, low complexity, no privileges required, but requiring user interaction and causing limited integrity impact. Although no active exploitation in the wild has been reported, the public availability of an exploit increases the risk of targeted attacks. The vulnerability affects only version 1.0 of the software, which is used for managing societies or community groups, implying that organizations relying on this system for administrative tasks are at risk. The lack of available patches necessitates immediate mitigation through secure coding practices and access controls.

For European organizations using itsourcecode Society Management System 1.0, this XSS vulnerability poses a risk to the confidentiality and integrity of administrative sessions. Attackers could leverage the flaw to steal session cookies, impersonate administrators, or perform unauthorized actions within the management system, potentially leading to data breaches or manipulation of society records. This could disrupt community management operations and damage organizational reputation. Given the administrative nature of the affected interface, exploitation could also facilitate further lateral movement or privilege escalation within the organization's network. The public availability of an exploit increases the likelihood of opportunistic attacks, especially in environments where administrators may be less security-aware. The impact is heightened in sectors where community data is sensitive or regulated under European data protection laws, such as GDPR, potentially leading to compliance violations and fines.

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. Since no official patch is currently available, applying Web Application Firewall (WAF) rules to detect and block typical XSS payloads targeting this parameter can provide interim protection. Restrict access to the admin interface by IP whitelisting or VPN-only access to reduce exposure. Educate administrators about the risks of clicking untrusted links and encourage the use of security-conscious browsing practices. Regularly monitor web server logs and application logs for suspicious requests containing script tags or unusual parameter values. Consider upgrading or migrating to a more secure version or alternative software if available. Finally, implement Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in the browser context.