CVE-2017-15284 in October
Summary
by MITRE
Cross-Site Scripting exists in OctoberCMS 1.0.425 (aka Build 425), allowing a least privileged user to upload an SVG file containing malicious code as the Avatar for the profile. When this is opened by the Admin, it causes JavaScript execution in the context of the Admin account.
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Analysis
by VulDB Data Team • 09/24/2025
This vulnerability represents a critical cross-site scripting flaw in OctoberCMS version 1.0.425 that demonstrates a dangerous privilege escalation vector through user avatar uploads. The vulnerability stems from inadequate input validation and sanitization of file uploads, specifically allowing SVG files to be uploaded without proper security measures. The flaw is categorized under CWE-79 as a failure to sanitize user-provided data, creating an environment where malicious scripts can be executed within the context of administrative sessions. Attackers can exploit this by uploading a specially crafted SVG file containing embedded javascript that executes when the administrator views the compromised profile page.
The technical implementation of this vulnerability exploits the trust relationship between the application and its users, particularly targeting the administrative interface where elevated privileges exist. When an administrator accesses a profile page displaying the malicious avatar, the SVG file executes JavaScript code within the admin context, potentially leading to complete account compromise. This represents a sophisticated attack vector that leverages the principle of least privilege by allowing a low-privilege user to gain administrative capabilities through a seemingly innocuous file upload functionality. The vulnerability specifically affects the avatar upload feature in OctoberCMS, which lacks proper file type validation and content sanitization mechanisms.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform actions with administrative privileges including but not limited to modifying user permissions, accessing sensitive data, and potentially compromising the entire application infrastructure. The attack requires minimal user interaction beyond uploading the malicious file, making it particularly dangerous in environments where administrators frequently view user profiles. This vulnerability aligns with ATT&CK technique T1059.007 for command and control through script-based payloads, and T1548.001 for privilege escalation by executing code in elevated contexts. The exploitation process demonstrates a classic server-side vulnerability where client-side validation is bypassed, allowing malicious content to persist and execute within the application's trusted environment.
Mitigation strategies should focus on implementing comprehensive file validation mechanisms including strict MIME type checking, content inspection for embedded scripts, and sanitization of uploaded files before storage. Organizations should implement proper input validation at multiple layers including client-side and server-side checks, employ Content Security Policy headers to prevent script execution, and conduct regular security audits of file upload functionalities. The vulnerability highlights the importance of treating all user-provided content as potentially malicious and implementing defense-in-depth strategies that include file type restrictions, size limitations, and automatic content analysis. Regular security updates and patch management are essential to address similar vulnerabilities in web application frameworks and prevent exploitation of known attack vectors.