CVE-2026-100630 in AVideo
Summary
by MITRE • 09/26/2026
AVideo contains a stored cross-site scripting vulnerability in the video trailer1 field rendered unsanitized within an inline onclick JavaScript string. Attackers with video upload permission can store HTML entity-encoded payloads that bypass isValidURL() validation and are decoded by the browser to break out of the JavaScript string, executing arbitrary code in any visitor's session including administrators.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/26/2026
The vulnerability identified in AVideo represents a critical stored cross-site scripting flaw located within the video trailer1 field. This security defect arises from insufficient input sanitization and validation mechanisms when processing user-supplied data for video metadata. Specifically, the application fails to properly escape or neutralize special characters before embedding them into inline JavaScript event handlers. The technical root cause lies in the interaction between the isValidURL() function and the browser's HTML parsing engine. Attackers can craft payloads using HTML entity encoding that successfully bypasses the server-side URL validation logic because the encoded entities are not interpreted as malicious during the initial check but are subsequently decoded by the client-side environment. This allows the payload to be stored in the database without triggering immediate rejection, creating a persistent threat vector within the application's content management system.
From an operational perspective, this vulnerability poses severe risks due to its persistence and broad impact scope. Since the malicious code is stored on the server, it executes automatically whenever any user views the affected video trailer page. This includes not only regular viewers but also administrative users who access their dashboards or manage video content. The ability of attackers with basic upload permissions to execute arbitrary JavaScript in the context of an administrator's session enables full account compromise. Attackers can steal session cookies, perform actions on behalf of the victim such as modifying settings or uploading further malware, and exfiltrate sensitive data from the platform. This effectively undermines the integrity and confidentiality of the entire AVideo deployment by allowing low-privilege users to escalate their privileges through client-side code execution.
The technical classification of this flaw aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. More specifically, it falls under Stored XSS where the malicious script is permanently stored within target servers such as in a database or message board. The exploitation technique leverages HTML entity encoding to evade basic validation filters, demonstrating how naive string handling can lead to context switching vulnerabilities where input intended for one context (a URL field) is interpreted in another (JavaScript code). This aligns with MITRE ATT&CK techniques related to Client-side Scripting Injection and potentially Account Manipulation if used to alter administrative configurations. The bypass of isValidURL() highlights a common pitfall in web application development where validation logic does not account for encoding layers that might obscure malicious intent during the check phase but reveal it upon rendering.
Mitigation strategies must address both immediate remediation and long-term defensive coding practices. Developers should implement strict output encoding tailored to the specific context of the data insertion, ensuring that characters like quotes, brackets, and ampersands are properly escaped before being placed within JavaScript strings or HTML attributes. Input validation should be enhanced to reject any input containing encoded entities if they are not expected in URL fields, or alternatively, use allowlists for permitted characters rather than relying solely on blocklist approaches which can often be bypassed via encoding tricks. Additionally, implementing Content Security Policy headers can significantly reduce the impact of such vulnerabilities by restricting the sources from which scripts can be loaded and executed. Regular security audits focusing on data flow analysis between user input points and sensitive output contexts are essential to identify similar latent flaws in other parts of the application architecture.