CVE-2026-48953 in Joomla! CMS
Summary
by MITRE • 07/07/2026
Lack of escaping leads to an XSS vulnerability in the generic image output layout.
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Analysis
by VulDB Data Team • 07/07/2026
This vulnerability represents a classic cross-site scripting flaw that arises from insufficient input sanitization within the image output rendering system. The absence of proper escaping mechanisms allows malicious actors to inject arbitrary script code into image-related content, which then executes within the context of other users' browsers when they view the affected pages. The vulnerability specifically manifests in generic image output layouts where user-supplied data flows directly into HTML generation without appropriate encoding or sanitization processes.
The technical root cause stems from improper handling of dynamic content within HTML contexts, particularly affecting image tags and their associated attributes such as src, alt, or title fields. When user input containing script code is processed through the image layout system without proper escaping, the browser interprets the injected payload as executable JavaScript rather than static text. This vulnerability aligns with CWE-79 which categorizes cross-site scripting as a critical weakness in web applications and maps to ATT&CK technique T1190 targeting web application vulnerabilities for initial access.
The operational impact of this vulnerability extends beyond simple script execution, potentially enabling attackers to steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious sites. Attackers can exploit this by uploading images with malicious payloads in their metadata or by manipulating image URLs to include harmful javascript code within the output layout. The vulnerability affects any application that dynamically generates image HTML output without proper input validation and sanitization, making it particularly dangerous in content management systems, forums, or any platform where users can upload media content.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. Immediate fixes involve implementing proper HTML escaping for all dynamic content within image layouts using context-appropriate encoding mechanisms such as HTML entity encoding for attributes and text content. Applications should employ Content Security Policy headers to limit script execution capabilities and implement strict input validation that filters out potentially malicious characters or patterns from user-supplied data. Additionally, regular security testing including dynamic application security testing and manual code reviews focused on output encoding practices can help identify similar vulnerabilities in other parts of the application. The solution must also consider implementing proper image processing pipelines that strip or sanitize metadata before rendering images to prevent embedded malicious content from being executed.