CVE-1999-0427 in Eudora
Summary
by MITRE
Eudora 4.1 allows remote attackers to perform a denial of service by sending attachments with long file names.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability described in CVE-1999-0427 affects Eudora 4.1 email client software and represents a classic denial of service weakness that exploits improper input validation mechanisms. This issue specifically targets the software's handling of email attachments with excessively long file names, creating a scenario where remote attackers can disrupt normal email processing operations. The vulnerability exists within the client-side application processing logic rather than network protocols, making it a software implementation flaw that affects end-user email clients rather than server infrastructure.
The technical flaw manifests when Eudora 4.1 encounters email messages containing attachments with file names that exceed the application's internal buffer or string handling limits. When processing these malformed attachments, the email client fails to properly validate the length of file names before attempting to store or display them, leading to buffer overflow conditions or memory allocation failures. This type of vulnerability falls under CWE-122, which describes buffer overflow conditions that occur when a program writes more data to a buffer than it can hold, and specifically relates to improper input validation. The flaw demonstrates poor defensive programming practices where the application does not implement adequate bounds checking or input sanitization before processing user-provided data.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise user productivity and system reliability in environments where Eudora 4.1 serves as the primary email client. When exploited, the denial of service condition can cause the email client to crash, freeze, or become unresponsive, forcing users to restart the application and potentially lose unsaved work. This vulnerability particularly affects organizations that rely on Eudora 4.1 for email communication, as attackers can systematically send malicious emails to disrupt email services across multiple users. The attack vector is straightforward requiring only that an attacker send an email with an attachment containing an excessively long file name, making it a low-effort, high-impact exploit that can be automated.
From a cybersecurity framework perspective, this vulnerability aligns with ATT&CK technique T1499.001 which covers network denial of service attacks, and demonstrates the importance of input validation controls as outlined in the OWASP Top Ten. The vulnerability highlights the need for robust application security practices including proper buffer management, input length validation, and defensive programming techniques. Organizations should implement email filtering solutions that can detect and block messages with suspiciously long file names, while also ensuring that legacy email clients receive appropriate security updates or are migrated to more modern, secure alternatives. The remediation approach involves both immediate application patches to fix the buffer handling logic and longer-term architectural changes to improve input validation across all email processing components.