CVE-2026-48954 in Joomla! CMS
Summary
by MITRE • 07/07/2026
Improper validation leads to a generic XSS vector in the language override feature.
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Analysis
by VulDB Data Team • 07/07/2026
This vulnerability represents a classic cross-site scripting weakness that arises from inadequate input sanitization within the application's language override functionality. The flaw occurs when user-supplied parameters intended for language configuration are not properly validated or escaped before being rendered back to users through web interfaces. This creates an opportunity for malicious actors to inject arbitrary javascript code that executes in the context of other users' browsers, effectively establishing a persistent XSS vector.
The technical implementation of this vulnerability typically involves the application accepting language identifiers or locale parameters through query strings, form fields, or cookies without proper sanitization. When these unvalidated inputs are subsequently embedded into web pages without appropriate encoding or escaping mechanisms, they become susceptible to malicious injection attacks. The vulnerability is particularly concerning because language override features are often used in internationalized applications and may be accessible through multiple entry points including API endpoints, configuration interfaces, and user preference settings.
From an operational perspective this vulnerability can have severe consequences including session hijacking, credential theft, data exfiltration, and establishment of backdoor access points. Attackers can leverage this vector to steal authentication tokens, capture sensitive user information, or redirect victims to malicious sites. The impact extends beyond individual user compromise as attackers can use this vulnerability to persistently target multiple users within the application ecosystem. This type of vulnerability often aligns with CWE-79 - Cross-site Scripting and may map to ATT&CK techniques such as T1566.001 - Phishing via Social Media and T1071.004 - Application Layer Protocol: DNS.
The remediation strategy must focus on implementing comprehensive input validation and output encoding mechanisms. All user-supplied parameters used in language override features should undergo strict validation against whitelisted acceptable values, with any invalid inputs being rejected or sanitized. Additionally, proper HTML entity encoding must be applied to all dynamic content before rendering to prevent script execution. Implementing Content Security Policy headers can provide additional defense-in-depth measures, while regular security testing including automated scanning and manual penetration testing should verify the effectiveness of implemented controls. The vulnerability demonstrates the critical importance of secure input handling in internationalization features and highlights how seemingly benign configuration options can become attack vectors when proper security controls are absent.