CVE-2025-48700 in Collaboration Suite
Summary
by MITRE • 06/23/2025
An issue was discovered in Zimbra Collaboration (ZCS) 8.8.15 and 9.0 and 10.0 and 10.1. A Cross-Site Scripting (XSS) vulnerability in the Zimbra Classic UI allows attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information. This issue arises from insufficient sanitization of HTML content, specifically involving crafted tag structures and attribute values that include an @import directive and other script injection vectors. The vulnerability is triggered when a user views a crafted e-mail message in the Classic UI, requiring no additional user interaction.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability identified as CVE-2025-48700 represents a critical cross-site scripting flaw within Zimbra Collaboration Suite versions 8.8.15 through 10.1, specifically affecting the Zimbra Classic UI interface. This security weakness stems from inadequate input validation and output sanitization mechanisms that fail to properly filter malicious HTML content. The flaw manifests when users access specially crafted email messages through the classic user interface, creating an attack vector that can be exploited without requiring any additional user interaction beyond viewing the malicious content. The vulnerability impacts the core authentication and session management functions of the email platform, potentially allowing attackers to hijack user sessions and gain unauthorized access to sensitive email communications and personal information.
The technical implementation of this XSS vulnerability involves the exploitation of HTML content sanitization failures that permit crafted tag structures and attribute values to bypass security filters. Specifically, attackers can embed @import directives and other script injection vectors within email messages that are subsequently rendered in the Classic UI. The vulnerability leverages the browser's interpretation of HTML content where malicious JavaScript code becomes executable within the context of the authenticated user's session. This occurs because the application fails to properly sanitize or escape HTML elements that contain potentially dangerous attributes or content that could trigger script execution when rendered. The flaw is particularly concerning as it operates entirely within the client-side rendering environment, making it difficult to detect through traditional network-based security measures.
The operational impact of CVE-2025-48700 extends beyond simple script execution, potentially enabling sophisticated attacks that can compromise entire user sessions and access sensitive data within the Zimbra environment. Attackers can exploit this vulnerability to steal session cookies, execute unauthorized commands, redirect users to malicious websites, or extract confidential email content and personal information. The vulnerability affects all users who access the Classic UI interface, making it a widespread concern across organizations utilizing these Zimbra versions. Given that the attack requires no user interaction beyond viewing the malicious email, it represents a significant risk for organizations where email remains a primary communication channel. The potential for privilege escalation and data exfiltration makes this vulnerability particularly dangerous in enterprise environments where sensitive corporate information is regularly transmitted through email systems.
Organizations affected by this vulnerability should implement immediate mitigations including upgrading to patched versions of Zimbra Collaboration Suite where available, implementing web application firewalls to detect and block malicious payloads, and applying input validation rules to prevent HTML content injection. Security teams should also consider implementing content security policies that restrict script execution within the email client interface and monitor for unusual user behavior that might indicate session hijacking attempts. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications, and represents a typical ATT&CK technique under T1059.007 for script execution through web interfaces. Organizations should conduct comprehensive security assessments of their email infrastructure and implement regular vulnerability scanning to identify similar sanitization issues that might exist in other components of their email systems.