CVE-2023-43319 in WebClient
Summary
by MITRE • 09/25/2023
Cross Site Scripting (XSS) vulnerability in the Sign-In page of IceWarp WebClient 10.3.5 allows attackers to execute arbitrary web scripts or HTML via a crafted payload injected into the username parameter.
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Analysis
by VulDB Data Team • 02/05/2026
The vulnerability identified as CVE-2023-43319 represents a critical cross site scripting flaw within the IceWarp WebClient version 10.3.5 authentication interface. This weakness resides specifically in the sign-in page where user credentials are processed, creating an avenue for malicious actors to inject harmful scripts into the application's web interface. The vulnerability manifests when an attacker crafts a malicious payload and submits it through the username parameter, bypassing normal input validation mechanisms that should prevent such injections from being processed.
The technical nature of this flaw aligns with CWE-79 which specifically addresses cross site scripting vulnerabilities where untrusted data is improperly integrated into web pages without proper sanitization or encoding. This particular implementation allows attackers to execute arbitrary JavaScript code within the context of the victim's browser session, potentially compromising user accounts and accessing sensitive information. The vulnerability exploits the web client's failure to properly validate and sanitize user input before rendering it back to the browser, creating a persistent threat vector that can be leveraged for session hijacking, credential theft, or redirection to malicious sites.
The operational impact of this vulnerability extends beyond simple script execution as it fundamentally undermines the security posture of the IceWarp WebClient environment. An attacker could craft payloads that steal session cookies, redirect users to phishing sites, or even inject malicious code that persists across multiple user sessions. The attack surface is particularly concerning given that the vulnerability targets the authentication page, which represents the primary entry point for legitimate users and therefore provides attackers with an ideal opportunity to gain unauthorized access to the system. This flaw can be exploited by both authenticated and unauthenticated attackers, making it particularly dangerous in environments where the web client is accessible to external users.
Mitigation strategies for CVE-2023-43319 should prioritize immediate implementation of input validation and output encoding mechanisms within the IceWarp WebClient application. Organizations should implement proper parameter sanitization for all user inputs, particularly those processed through authentication interfaces, and apply Content Security Policy headers to limit script execution capabilities. The fix should involve comprehensive input validation that rejects or encodes potentially malicious characters, along with proper output encoding for all dynamic content rendered in the browser. Security teams should also consider implementing web application firewalls that can detect and block suspicious payload patterns targeting the username parameter, while also monitoring for unusual authentication attempts that might indicate exploitation attempts. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other application components, as this flaw demonstrates a broader pattern of insufficient input sanitization in web applications. The vulnerability serves as a reminder of the critical importance of implementing defense-in-depth strategies that include both runtime protections and proactive security measures to prevent similar issues from occurring in other components of the web application ecosystem.