CVE-2025-52557 in Zero
Summary
by MITRE • 06/21/2025
Mail-0's Zero is an open-source email solution. In version 0.8 it's possible for an attacker to craft an email that executes javascript leading to session hijacking due to improper sanitization. This issue has been patched in version 0.81.
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Analysis
by VulDB Data Team • 06/21/2025
The vulnerability identified as CVE-2025-52557 affects Mail-0's Zero, an open-source email solution that has become a target for cyber adversaries seeking to exploit weaknesses in email processing systems. This particular vulnerability resides within version 0.8 of the software and represents a critical security flaw that could enable attackers to execute malicious javascript code through crafted email messages. The issue stems from inadequate input validation and sanitization mechanisms within the email processing pipeline, creating a pathway for arbitrary code execution that could compromise user sessions and lead to unauthorized access to sensitive email communications.
The technical flaw manifests as a failure to properly sanitize user-supplied input within email messages, specifically in the handling of HTML content and embedded javascript code. When the vulnerable system processes an email containing malicious javascript within its body or attachments, the insufficient sanitization allows the code to execute within the context of the user's browser session. This vulnerability directly maps to CWE-79, which describes Cross-Site Scripting (XSS) flaws where untrusted data is improperly incorporated into web pages without adequate validation or escaping. The attack vector likely involves crafting emails with embedded javascript payloads that exploit the lack of proper content filtering mechanisms in the email client's rendering engine.
The operational impact of this vulnerability extends beyond simple script execution, as it creates a pathway for session hijacking attacks that could allow adversaries to impersonate legitimate users within the email system. When javascript code executes within a user's browser session, attackers can potentially access cookies, session tokens, and other authentication mechanisms that would normally protect user accounts. This could result in unauthorized access to email accounts, data exfiltration, and the ability to send emails on behalf of compromised users. The vulnerability's severity is amplified by its potential for automated exploitation, as attackers could craft emails that automatically execute malicious code without requiring user interaction beyond opening the message.
Organizations utilizing Mail-0's Zero version 0.8 should immediately implement mitigations including updating to version 0.81, which contains the necessary patches to address the sanitization issues. Additional protective measures include implementing strict email content filtering policies, enabling sandboxing for email rendering, and deploying web application firewalls that can detect and block suspicious javascript patterns. The ATT&CK framework categorizes this vulnerability under T1566, which covers social engineering techniques, and T1059, which covers command and scripting interpreters. Security teams should also consider implementing email security solutions that provide additional layers of protection against malicious content, including sandboxing email attachments and monitoring for suspicious javascript patterns in incoming messages. Regular security assessments and penetration testing should be conducted to ensure that similar vulnerabilities are not present in other components of the email infrastructure.