CVE-2000-0105 is a medium-severity vulnerability affecting Microsoft Outlook Express 5.01 and Internet Explorer 5.01. The flaw allows remote attackers to view a user's email messages without authorization by exploiting a scripting issue. Specifically, a malicious script can access a variable that references subsequent email messages read by the client, thereby exposing the content of those emails. This vulnerability arises from insufficient access controls in the way these applications handle scripting and email message references. Since the attack vector is network-based (AV:N), no authentication is required (Au:N), and the attack complexity is low (AC:L), an attacker can remotely execute a script to read email contents without user interaction. However, the impact is limited to confidentiality (C:P), with no effect on integrity or availability. The affected products are legacy software versions released around 1997-1998, and no patches are available for this vulnerability. There are no known exploits in the wild, likely due to the age of the software and its diminished usage. Nonetheless, the vulnerability represents a significant privacy risk for users still operating these outdated clients, as it could lead to unauthorized disclosure of sensitive email content.

For European organizations, the primary impact of CVE-2000-0105 is the potential unauthorized disclosure of sensitive or confidential email communications. This could lead to privacy violations, exposure of intellectual property, or leakage of personal data protected under regulations such as the GDPR. Although the affected software versions are very old and largely obsolete, some legacy systems or isolated environments might still use Outlook Express 5.01 or Internet Explorer 5.01, especially in industrial or governmental contexts where system upgrades are slow. In such cases, attackers could remotely access email content without detection, undermining trust and compliance with data protection laws. The lack of patches and the medium severity rating mean that organizations relying on these products face a persistent risk. However, the overall impact on availability and integrity is minimal, and exploitation does not require user interaction, increasing the risk of silent data breaches.

Given the absence of patches, the most effective mitigation is to discontinue the use of Outlook Express 5.01 and Internet Explorer 5.01 entirely. Organizations should upgrade to supported and actively maintained email clients and browsers that have robust security controls and receive regular updates. Network-level protections such as web content filtering and intrusion detection systems can help block malicious scripts attempting to exploit this vulnerability. Additionally, organizations should audit their environments to identify any legacy systems still running these outdated applications and isolate them from external networks or restrict their internet access. Implementing strict email security policies, including disabling scripting in email clients and browsers where possible, can reduce the attack surface. User awareness training about the risks of using unsupported software is also critical. Finally, organizations should monitor network traffic for unusual script activity targeting email clients to detect potential exploitation attempts.