CVE-1999-1155 is a high-severity remote code execution vulnerability affecting the LakeWeb Mail List CGI script. This vulnerability arises because the script fails to properly sanitize shell metacharacters in the recipient email address parameter. An attacker can exploit this flaw by injecting arbitrary shell commands into the recipient field, which the CGI script then executes on the server with the privileges of the web server process. Since the vulnerability requires no authentication and can be triggered remotely over the network, it poses a significant risk. The impact includes potential full compromise of the affected server, allowing attackers to execute arbitrary commands, manipulate data, disrupt services, or use the compromised system as a foothold for further attacks. The vulnerability dates back to 1998 and has a CVSS v2 base score of 7.5, indicating high severity with network attack vector, low attack complexity, no authentication required, and partial to complete impact on confidentiality, integrity, and availability. No patches or fixes are available, and no known exploits are currently reported in the wild, but the nature of the vulnerability makes it a critical concern for any legacy systems still running this software.

For European organizations, the impact of this vulnerability can be severe if legacy systems running the LakeWeb Mail List CGI script are still in use. Exploitation could lead to unauthorized command execution on mail servers, potentially resulting in data breaches, defacement, service disruption, or use of the compromised server as a pivot point for lateral movement within the network. This could affect confidentiality of sensitive communications, integrity of mailing lists and related data, and availability of mail services. Organizations in sectors with high reliance on email communications, such as government, finance, and critical infrastructure, could face operational disruptions and reputational damage. Additionally, compliance with GDPR and other data protection regulations could be jeopardized if personal data is exposed or manipulated due to exploitation of this vulnerability.

Given that no official patches are available, European organizations should take immediate steps to mitigate risk. First, identify and inventory any systems running the LakeWeb Mail List CGI script and isolate them from external network access if possible. Replace or upgrade the mail list management software with modern, actively maintained alternatives that properly sanitize user inputs. If replacement is not immediately feasible, implement strict input validation and sanitization at the web server or application firewall level to block shell metacharacters in email address parameters. Employ network-level protections such as web application firewalls (WAFs) configured to detect and block command injection attempts targeting CGI scripts. Regularly monitor logs for suspicious activity indicative of exploitation attempts. Finally, consider network segmentation to limit the impact of a potential compromise and ensure that affected systems run with the least privilege necessary.