CVE-2024-23525 is a vulnerability identified in the Perl module Spreadsheet::ParseXLSX versions prior to 0.30. This module is used for parsing XLSX spreadsheet files. The vulnerability arises from the module's failure to enable the 'no_xxe' option in the XML::Twig parser it uses internally. XML External Entity (XXE) attacks exploit weaknesses in XML parsers that allow external entities to be processed, potentially leading to exposure of sensitive data or denial of service. In this case, the absence of the 'no_xxe' option means that maliciously crafted XLSX files containing external entity references can cause the parser to access unintended resources or disclose confidential information. The CVSS 3.1 base score of 6.5 (medium severity) reflects that the attack vector is network-based, requires no privileges, but does require user interaction (opening or processing a malicious XLSX file). The impact is primarily on confidentiality, with no direct impact on integrity or availability. No known exploits are currently reported in the wild, and no patches or vendor-specific mitigations have been linked yet. The vulnerability is classified under CWE-611, which covers improper restriction of XML external entity references.

For European organizations, the impact of this vulnerability depends largely on the extent to which they use Perl applications or scripts that rely on the Spreadsheet::ParseXLSX module to process XLSX files, especially those obtained from untrusted sources. If exploited, attackers could leverage crafted XLSX files to read sensitive files or internal network resources accessible to the parsing environment, potentially leading to data leaks. This is particularly concerning for sectors handling sensitive or regulated data, such as finance, healthcare, and government agencies. Since the vulnerability requires user interaction (opening or processing the malicious file), phishing or social engineering campaigns could be used as attack vectors. The confidentiality breach could lead to regulatory compliance issues under GDPR if personal or sensitive data is exposed. However, the lack of impact on integrity and availability limits the scope of damage to data exposure rather than system disruption or data manipulation.

European organizations should audit their Perl-based applications and scripts to identify usage of the Spreadsheet::ParseXLSX module, especially versions prior to 0.30. Immediate mitigation involves upgrading to version 0.30 or later where the 'no_xxe' option is properly enabled to prevent XXE attacks. If upgrading is not immediately feasible, organizations should implement input validation and sandboxing measures to restrict the processing of untrusted XLSX files. Additionally, deploying file scanning solutions to detect and block malicious XLSX files can reduce risk. User awareness training to recognize phishing attempts involving spreadsheet attachments is also critical. For developers maintaining custom Perl scripts, explicitly setting the 'no_xxe' option in XML::Twig when parsing XLSX files is a direct and effective mitigation. Monitoring logs for unusual file processing activities and network requests triggered by XML parsing can help detect exploitation attempts.