CVE-2000-0105 in Internet Explorer
Summary
by MITRE
Outlook Express 5.01 and Internet Explorer 5.01 allow remote attackers to view a user's email messages via a script that accesses a variable that references subsequent email messages that are read by the client.
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Analysis
by VulDB Data Team • 04/20/2026
This vulnerability exists in Microsoft Outlook Express 5.01 and Internet Explorer 5.01 where a security flaw allows remote attackers to access email messages through malicious scripting techniques. The vulnerability stems from improper handling of email message variables within the client-side email processing framework, creating a cross-site scripting condition that enables unauthorized access to subsequent email messages. The flaw occurs when the email client processes scripts that reference message variables, allowing attackers to manipulate the message reading sequence and access messages that have not yet been viewed by the legitimate user. This represents a classic case of inadequate input validation and variable handling within email client applications.
The technical implementation of this vulnerability involves a script that accesses a variable containing references to email messages that have been read by the client. When Outlook Express or Internet Explorer processes such malicious scripts, the variable references become accessible to remote attackers who can exploit this behavior to view messages that would normally remain protected. The vulnerability is particularly dangerous because it operates at the client-side processing level, bypassing traditional server-side security controls. This type of flaw aligns with CWE-79 which addresses cross-site scripting vulnerabilities, and more specifically with CWE-20 which deals with improper input validation. The attack vector leverages the trust relationship between the email client and the scripting environment, making it particularly insidious.
The operational impact of this vulnerability is significant as it allows attackers to compromise user privacy and potentially access sensitive information contained in email communications. Remote attackers can exploit this vulnerability without requiring local system access or authentication, making it a serious threat to email security. The vulnerability affects users who receive malicious emails containing the exploitable scripts, potentially exposing confidential business communications, personal information, or sensitive data. This type of attack falls under the ATT&CK technique T1059.007 which covers script-based execution, and specifically targets the credential access and information gathering phases of the attack lifecycle. The vulnerability essentially creates a backdoor for attackers to access email content that should remain private to the legitimate user.
Mitigation strategies for this vulnerability include immediate installation of security patches provided by Microsoft, which would address the variable handling and script processing issues within the email client. Users should also implement strict email filtering policies that block potentially malicious scripts from entering the email environment. Network administrators should consider implementing email content filtering solutions that can detect and prevent the delivery of exploit payloads targeting this specific vulnerability. The recommended approach includes disabling script execution in email clients where possible, implementing proper input validation for email content, and maintaining current security updates for all email client applications. Additionally, user education regarding the dangers of opening emails from unknown sources and the importance of keeping software updated can significantly reduce the risk of exploitation. Organizations should also consider implementing email encryption solutions to protect sensitive communications even if client-side vulnerabilities are exploited.