CVE-2018-5753 in OX AppSuite
Summary
by MITRE
The frontend component in Open-Xchange OX App Suite before 7.6.3-rev31, 7.8.x before 7.8.2-rev31, 7.8.3 before 7.8.3-rev41, and 7.8.4 before 7.8.4-rev20 allows remote attackers to spoof the origin of e-mails via unicode characters in the "personal part" of a (1) From or (2) Sender address.
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Analysis
by VulDB Data Team • 11/25/2025
The vulnerability identified as CVE-2018-5753 affects the Open-Xchange OX App Suite email system and represents a significant security flaw in the frontend component that handles email address parsing and display. This issue specifically targets the handling of unicode characters within the personal name portion of email addresses, creating a potential avenue for malicious actors to manipulate email metadata in ways that could deceive recipients and bypass security controls. The vulnerability impacts multiple version ranges including 7.6.3-rev31, 7.8.2-rev31, 7.8.3-rev41, and 7.8.4-rev20, indicating a widespread issue that affected various releases of the email platform.
The technical flaw stems from insufficient validation and sanitization of unicode characters in email address personal names, particularly within the From and Sender header fields. When an attacker crafts an email address with unicode characters in the personal part of the address, the system fails to properly normalize or validate these characters, allowing for the creation of addresses that appear legitimate but actually originate from different sources. This occurs because the email client displays the unicode characters in a way that mimics legitimate addresses while the underlying technical address may be completely different, enabling sophisticated social engineering attacks that exploit the trust users place in familiar email formats.
The operational impact of this vulnerability extends beyond simple email spoofing and creates serious security implications for organizations relying on email-based authentication and verification processes. Attackers can exploit this weakness to create convincing phishing emails that appear to originate from trusted internal sources or partners, potentially bypassing email filtering systems that rely on address validation. The vulnerability particularly affects email systems that depend on the From or Sender header fields for security decisions, potentially allowing attackers to circumvent security controls that should prevent unauthorized access or impersonation. This flaw can be leveraged in targeted attacks where attackers craft emails that appear to come from legitimate internal addresses, increasing the likelihood of successful social engineering and credential theft attempts.
Organizations affected by this vulnerability should immediately implement mitigations including updating to the patched versions of OX App Suite, specifically versions 7.6.3-rev31, 7.8.2-rev31, 7.8.3-rev41, and 7.8.4-rev20 or later releases. Additional protective measures include implementing stricter email header validation policies, deploying enhanced email filtering solutions that can detect and block suspicious unicode character sequences, and conducting user awareness training to recognize potential spoofing attempts. The vulnerability aligns with CWE-174, which addresses the issue of insufficient input validation, and can be categorized under ATT&CK technique T1566 for phishing campaigns that exploit email spoofing capabilities. Security teams should also consider implementing email authentication mechanisms such as SPF, DKIM, and DMARC to provide additional layers of protection against this type of spoofing attack, as these protocols can help verify the authenticity of email sources and detect malformed addresses that exploit this vulnerability.