CVE-2023-51769 in Frappe
Summary
by MITRE • 09/14/2026
Frappe before 14.49.0 allows an XSS attack that is associated with blog pages and exception pages.
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Analysis
by VulDB Data Team • 09/14/2026
The vulnerability identified in Frappe versions prior to 14.49.0 represents a significant security risk centered on Cross-Site Scripting, commonly referred to as XSS. This flaw specifically targets the rendering mechanisms of blog posts and system-generated exception pages within the Frappe framework. As an open-source low-code platform widely used for building business applications, Frppe relies heavily on server-side rendering and dynamic content injection. When a user interacts with these specific components, particularly through input fields or URL parameters that are reflected back into the HTML response without adequate sanitization, malicious scripts can be injected. The absence of proper output encoding allows an attacker to execute arbitrary JavaScript in the context of the victim's browser session.
From a technical perspective, this vulnerability stems from insufficient validation and escaping of user-supplied data before it is rendered by the web application. In the case of blog pages, content often includes rich text or metadata that may be processed dynamically. Similarly, exception pages are designed to display error messages and stack traces to aid in debugging, but they frequently reflect input directly into the DOM without applying strict Content Security Policy constraints or HTML entity encoding. This allows an attacker to craft a malicious payload that bypasses basic filters and executes within the browser environment of any user who views the compromised page. The attack vector is typically classified as stored or reflected XSS depending on whether the malicious content is persisted in the database or merely echoed back in the immediate HTTP response, both of which fall under the broader category of injection flaws where untrusted data is sent to a web interpreter without proper neutralization.
The operational impact of this vulnerability extends beyond simple script execution. An attacker leveraging this XSS flaw can perform session hijacking by stealing authentication cookies and tokens stored in the browser's local storage or cookie jar. This enables unauthorized access to user accounts, potentially escalating privileges if the targeted account has administrative rights within the Frappe instance. Furthermore, the attacker could manipulate page content, redirect users to phishing sites, or deploy keyloggers to capture sensitive credentials entered on subsequent pages. In enterprise environments where Frppe is used for critical business operations such as ERPNext, this compromise can lead to data exfiltration, integrity violations of stored records, and a complete breakdown of trust in the application's security posture. The ability to execute scripts also facilitates drive-by downloads or exploitation of other browser-side vulnerabilities if combined with additional attack vectors.
To mitigate this vulnerability, organizations must immediately upgrade their Frappe installations to version 14.49.0 or later, where these input validation and output encoding issues have been addressed by the development team. For environments that cannot be updated instantly due to compatibility constraints, implementing a Web Application Firewall is recommended to filter out known XSS payloads in HTTP requests and responses. Additionally, developers should enforce strict Content Security Policy headers that restrict script execution sources and disable inline scripts where possible. Input validation must be applied at both the client and server sides, ensuring that all user inputs are sanitized against expected formats before processing. Output encoding should be context-aware, utilizing appropriate escaping techniques for HTML bodies, attributes, JavaScript contexts, and CSS properties to prevent interpretation of injected data as executable code. Regular security audits and static application security testing can help identify similar patterns in custom modules or third-party apps integrated with the Frappe framework.
This vulnerability aligns with CWE-79, which defines Improper Neutralization of Input During Web Page Generation, a standard classification for cross-site scripting flaws. In terms of offensive tactics, it maps to MITRE ATT&CK technique T1059, specifically sub-technique 007 for JavaScript execution, and potentially T1204 if used as part of user execution campaigns where social engineering tricks users into visiting the malicious page. Understanding these mappings helps security teams prioritize remediation efforts based on industry-standard risk frameworks and ensures that defensive measures are aligned with recognized best practices for web application security.