CVE-2026-89307 in Design Scuole Italia Plugin
Summary
by MITRE • 09/15/2026
The "Firma Circolare" feature in the "Design Scuole Italia" WordPress theme allows an authenticated attacker to inject arbitrary HTML via the sign parameter, enabling forced redirection of visiting users to an attacker-controlled URL (Stored HTML Injection / Open Redirect).
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability identified within the Design Schools Italy WordPress theme centers on a critical flaw in the Firma Circolare feature, which permits stored cross-site scripting and open redirect attacks. This security issue arises from insufficient input validation and sanitization mechanisms applied to the sign parameter during data processing operations. Because the application fails to properly encode or filter user-supplied content before storing it in the database, an authenticated attacker can inject arbitrary HTML code into the system. The persistence of this malicious payload distinguishes it as a stored vulnerability rather than a reflected one, meaning that the injected script is saved on the server and executed every time a victim accesses the affected page. This architectural flaw allows the threat actor to manipulate the client-side behavior of any user who views the compromised content without requiring further interaction from the attacker at the moment of exploitation.
From an operational perspective, this vulnerability enables forced redirection of visiting users to URLs controlled by the attacker. By embedding HTML elements such as image tags or script redirects within the sign parameter, the attacker can trigger immediate navigation away from the legitimate application environment. This mechanism is particularly dangerous in enterprise and educational contexts where trust in the domain is high. Users who are redirected may be led to phishing sites designed to harvest credentials, download malware payloads, or engage in social engineering attacks that exploit their perceived legitimacy of the source. The impact extends beyond individual compromise, potentially affecting institutional reputation and data integrity if sensitive information is exfiltrated through these deceptive redirects.
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 (XSS). Specifically, the stored nature of the injection places it within the subset of persistent XSS vulnerabilities that pose a higher risk due to their broad impact on multiple users. Additionally, the capability to force redirection maps directly to CWE-601 URL Redirection to Untrusted Site Open Redirect and ATT&CK technique T1566.002 Spearphishing Link. These mappings highlight the dual nature of the vulnerability as both a code injection issue and an access control bypass mechanism that leverages social engineering through deceptive navigation patterns.
Mitigation strategies must focus on rigorous input validation and output encoding practices within the theme's development lifecycle. Developers should implement strict allow-listing for permitted characters in the sign parameter to prevent HTML tag insertion entirely if such functionality is not required. If rich text input is necessary, robust sanitization libraries compliant with OWASP guidelines should be employed to strip dangerous tags while preserving legitimate formatting. Furthermore, implementing Content Security Policy headers can mitigate the impact of any successfully injected scripts by restricting source domains for execution and navigation actions. Regular security audits and penetration testing focused on authenticated user inputs are essential to identify similar flaws in other features that may share this architectural weakness.