CVE-2004-1521 in Eudora
Summary
by MITRE
Eudora 6.2.0.14 does not issue a warning when a user forwards an e-mail message that contains base64 or quoted-printable encoded attachments, which makes it easier for remote attackers to read arbitrary files via spoofed "Converted" headers.
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Analysis
by VulDB Data Team • 09/04/2025
The vulnerability described in CVE-2004-1521 affects Eudora email client version 6.2.0.14 and represents a significant security flaw in how the application handles email message forwarding operations. This issue stems from the client's failure to properly validate or warn users about the presence of encoded attachments when messages are forwarded, creating a potential vector for unauthorized file access through carefully crafted email spoofing techniques. The vulnerability operates at the application level within the email client's message processing and forwarding mechanisms, specifically targeting how the software interprets and displays message headers during forwarding operations.
The technical implementation of this vulnerability involves the client's handling of base64 and quoted-printable encoded attachments within email messages. When users forward messages containing these encoded attachments, Eudora does not issue any warning or notification about the presence of encoded content that might be manipulated by attackers. This behavior creates a scenario where remote attackers can craft malicious email messages with spoofed "Converted" headers that appear legitimate to the end user. The flaw essentially allows attackers to bypass normal security checks that would typically prevent users from accessing potentially harmful file content through email forwarding operations.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables sophisticated social engineering attacks and file access exploitation techniques. Attackers can leverage this weakness to trick users into forwarding messages containing encoded attachments that, when processed by the vulnerable client, may reveal sensitive information or allow access to arbitrary files on the user's system. The vulnerability particularly affects environments where users frequently forward email messages and where security awareness may be limited. This issue represents a classic case of insufficient input validation and inadequate user warnings in email client applications, which aligns with CWE-20 - Improper Input Validation and CWE-170 - Improper Null Termination.
Security professionals should note that this vulnerability demonstrates the importance of proper email client security implementations, particularly regarding how applications handle message forwarding and header processing. The flaw essentially allows attackers to exploit the trust users place in forwarded messages, enabling them to potentially access files that would normally be protected from casual inspection. This type of vulnerability is particularly dangerous in corporate environments where employees frequently forward internal communications and may not recognize the security implications of forwarding messages with encoded content. Mitigation strategies should focus on user education, email client updates, and implementation of email filtering systems that can detect and block suspicious header modifications. The vulnerability also highlights the need for adherence to security best practices in email client development and aligns with ATT&CK techniques related to social engineering and credential access through email manipulation.