CVE-2026-26483 in SendPortal
Summary
by MITRE • 07/20/2026
Mettle SendPortal 3.0.1 and earlier contains a stored cross-site scripting (XSS) vulnerability in the template management functionality. The application fails to properly sanitize user-supplied input in the content parameter of the /templates endpoint, allowing an attacker to persistently inject malicious JavaScript code that is executed in the browsers of users who access the affected template.
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Analysis
by VulDB Data Team • 07/20/2026
The stored cross-site scripting vulnerability in Mettle SendPortal versions 3.0.1 and earlier represents a critical security flaw that undermines the integrity of user sessions and data confidentiality. This vulnerability exists within the template management functionality, specifically in how the application processes user-supplied input through the content parameter of the /templates endpoint. The flaw allows attackers to inject malicious JavaScript code that persists within the application's database, making it executable whenever users interact with affected templates.
The technical implementation of this vulnerability stems from inadequate input validation and output sanitization mechanisms within the template management system. When administrators or authorized users create or modify templates through the web interface, the application accepts content parameters without sufficient sanitization of potentially malicious code. This failure to properly escape or filter user input creates an environment where attacker-controlled JavaScript can be stored and later executed in the browsers of legitimate users who view these templates.
From an operational perspective, this vulnerability poses significant risks to organizations using Mettle SendPortal for email template management and content delivery. An attacker who gains access to template creation functionality can inject malicious scripts that may perform various harmful actions including session hijacking, credential theft, data exfiltration, or redirection to phishing sites. The stored nature of the vulnerability means that once injected, the malicious code remains persistent and will execute automatically for any user who accesses the affected templates, potentially affecting large numbers of users simultaneously.
The impact extends beyond immediate security breaches as this vulnerability can facilitate more sophisticated attack chains. According to the mitre att&ck framework, this represents a stored xss technique (t1065) that can lead to privilege escalation and lateral movement within affected environments. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications, and demonstrates how insufficient input validation creates persistent security risks.
Organizations should implement immediate mitigations including input validation at multiple layers, output encoding for all template content, and regular security assessments of template management systems. The recommended approach involves implementing proper sanitization of user inputs, establishing strict content validation rules, and monitoring template access logs for suspicious activities. Additionally, organizations should consider implementing web application firewalls and regular security training for administrators to prevent unauthorized template modifications that could lead to exploitation of this stored XSS vulnerability.