CVE-2000-0455 is a buffer overflow vulnerability found in the xlockmore xlock program, specifically in version 4.16 and earlier. The vulnerability arises when a local user supplies an excessively long argument to the '-mode' option of the xlock program. This input is not properly bounds-checked, leading to a buffer overflow condition. Exploiting this flaw allows a local attacker to read sensitive data from the program's memory space. The vulnerability does not allow for code execution or privilege escalation but compromises confidentiality by exposing potentially sensitive information stored in memory. The vulnerability requires local access, meaning the attacker must have an account on the affected system. No authentication is required beyond local user access, and no user interaction beyond invoking the vulnerable program with crafted parameters is necessary. The vulnerability has a CVSS v2 base score of 2.1, indicating a low severity primarily due to the limited impact (confidentiality only) and the requirement for local access. There is no patch available for this vulnerability, and no known exploits have been reported in the wild. The affected product, xlockmore, is a screen-locking utility commonly used on Unix and Linux systems to lock the graphical user interface session. Given the age of the vulnerability (published in 2000) and the niche use of xlockmore, this vulnerability is largely of historical interest but may still be relevant in legacy or specialized environments.

For European organizations, the impact of this vulnerability is generally low due to several factors. The vulnerability requires local user access, which limits the attack surface to insiders or users with existing system accounts. The impact is limited to confidentiality, allowing reading of sensitive memory data but not modification or denial of service. Organizations using modern or actively maintained screen locking solutions are unlikely to be affected. However, legacy systems or specialized environments that still use xlockmore 4.16 or earlier could be at risk of sensitive information disclosure, which might include credentials, cryptographic keys, or other private data stored in memory. This could facilitate further attacks if combined with other vulnerabilities or insider threats. The absence of known exploits and patches reduces the immediate risk but also means organizations must rely on mitigating controls or replacement of the vulnerable software. Overall, the threat is low but should not be ignored in environments where xlockmore is still in use.

Replace xlockmore with a modern, actively maintained screen locking utility that does not have known vulnerabilities. Restrict local user access to systems where xlockmore is installed, ensuring only trusted users have accounts. Implement strict user privilege separation and monitoring to detect unusual usage of the xlock program. If replacement is not immediately feasible, consider disabling the '-mode' option or restricting command-line arguments via wrapper scripts or access controls to prevent exploitation. Conduct regular audits of legacy systems to identify and remediate outdated software components like xlockmore. Ensure that sensitive data is not stored in memory in plaintext or accessible formats to reduce the impact of memory disclosure vulnerabilities.