CVE-2026-50766 in Library Management System
Summary
by MITRE • 06/27/2026
A stored cross-site scripting (XSS) vulnerability in the OPAC item detail page of Koha Library Management System through 25.11 allows an authenticated remote attacker with edit_items permission to inject arbitrary web scripts via the item public notes field (items.itemnotes).
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Analysis
by VulDB Data Team • 06/27/2026
The vulnerability under examination represents a critical stored cross-site scripting flaw within the Koha Library Management System version 25.11 and earlier, specifically affecting the OPAC item detail page functionality. This security weakness resides in the handling of user-supplied data within the items.itemnotes field, which is designed to store public notes about library items. The vulnerability is particularly concerning because it requires only authenticated access with edit_items permissions, making it exploitable by insiders or compromised accounts rather than requiring external network access.
The technical implementation of this flaw occurs when the system fails to properly sanitize or escape user input before rendering it in the web interface. When an attacker with appropriate privileges submits malicious script code through the item public notes field, the system stores this content without adequate validation measures. During subsequent page rendering for any user viewing the OPAC item detail page, the stored malicious script executes within the browser context of the victim user, potentially leading to session hijacking, credential theft, or further exploitation of the web application.
This vulnerability has significant operational impact within library management environments where multiple users may have edit_items permissions. The stored nature of the XSS attack means that once exploited, the malicious payload persists and affects all subsequent visitors to the affected item detail pages until manually removed by administrators. The attack vector is particularly dangerous because it leverages legitimate user privileges, making detection more challenging for security monitoring systems that might not immediately flag authorized users as potential threats.
From a cybersecurity framework perspective, this vulnerability maps directly to CWE-79 "Improper Neutralization of Input During Web Page Generation" and aligns with ATT&CK technique T1566.001 "Phishing via System Application" in its exploitation methodology. The vulnerability also demonstrates characteristics consistent with ATT&CK technique T1059.001 "Command and Scripting Interpreter: PowerShell" when considering how malicious scripts might be constructed to leverage the XSS capability for further attack vectors.
Organizations should implement immediate mitigations including input validation and output sanitization measures that escape or filter all user-supplied content before storage and rendering. The recommended approach involves implementing a comprehensive content security policy that restricts script execution, utilizing proper HTML escaping mechanisms for all dynamic content, and establishing strict input validation rules for the items.itemnotes field. Additionally, privilege escalation should be carefully reviewed to ensure that only necessary users have edit_items permissions, and regular security audits should verify that no malicious scripts have been injected into the system.
Administrative remediation requires updating to patched versions of Koha 25.12 or later where this vulnerability has been addressed through proper input sanitization mechanisms. Organizations should also implement monitoring solutions that can detect anomalous content within public notes fields and establish incident response procedures for identifying and removing malicious payloads. The security architecture should incorporate defense-in-depth strategies including web application firewalls, regular penetration testing, and user access reviews to prevent unauthorized privilege escalation that could lead to exploitation of this vulnerability.