CVE-2025-8291 affects the 'zipfile' module in the Python Software Foundation's CPython implementation. The vulnerability arises because the module does not properly validate the offset value in the ZIP64 End of Central Directory (EOCD) Locator record. Instead of using the offset to locate the ZIP64 EOCD record, the module assumes the ZIP64 EOCD record is the previous record in the ZIP archive. This behavior can be exploited by attackers to craft ZIP archives that are interpreted differently by Python's 'zipfile' module compared to other ZIP implementations. Such discrepancies can lead to integrity issues where the contents extracted or processed by Python differ from those handled by other tools, potentially enabling evasion or manipulation in workflows relying on ZIP files. The remediation approach maintains the existing behavior but adds a validation step to ensure the offset in the ZIP64 EOCD Locator matches the expected value, preventing the discrepancy. The vulnerability has a CVSS 3.1 base score of 4.3, indicating medium severity, with an attack vector of network, low attack complexity, no privileges required, but requiring user interaction. There is no impact on confidentiality or availability, only a low impact on integrity. No known exploits are currently reported in the wild. This vulnerability primarily affects applications and systems that use Python's 'zipfile' module to process ZIP64 archives, which is common in many software environments.

For European organizations, the impact of CVE-2025-8291 is primarily related to data integrity during ZIP file processing. Applications that rely on Python's 'zipfile' module to extract or manipulate ZIP64 archives may incorrectly interpret archive contents, potentially leading to processing of unintended files or bypassing security checks that rely on ZIP file structure validation. This could affect software supply chains, automated deployment pipelines, or data ingestion systems that use ZIP files, causing subtle data manipulation or evasion of security controls. However, since there is no confidentiality or availability impact and exploitation requires user interaction (e.g., opening or processing a crafted ZIP file), the overall risk is moderate. European organizations with extensive Python usage in development, data processing, or automation environments should be aware of this vulnerability to avoid integrity issues and potential downstream effects on data quality or security. The lack of known exploits reduces immediate risk, but proactive patching and validation are advised.

1. Apply official patches or updates from the Python Software Foundation as soon as they become available to ensure the 'zipfile' module correctly validates the ZIP64 EOCD Locator offset. 2. Implement additional input validation and integrity checks on ZIP files before processing, especially for ZIP64 archives, to detect anomalies or inconsistencies in archive structure. 3. Use alternative ZIP processing libraries or tools with robust ZIP64 validation as a temporary workaround if patching is delayed. 4. Educate developers and system administrators about the risks of processing untrusted ZIP files and enforce strict controls on file sources. 5. Incorporate security scanning and fuzz testing of ZIP file handling in CI/CD pipelines to detect similar issues early. 6. Monitor Python environment versions across the organization to ensure vulnerable versions are identified and remediated promptly. 7. Restrict user interaction with untrusted ZIP files through endpoint protection and user awareness training to reduce exploitation likelihood.