CVE-2025-63914 identifies a vulnerability in the Cinnamon kotaemon 0.11.0 software, specifically in the _may_extract_zip function located in the \libs\ktem\ktem\index\file\ui.py file. The function does not perform adequate validation or inspection of the contents of uploaded ZIP files before extraction. Although the extraction occurs in a temporary folder that is cleared prior to each extraction, the vulnerability allows an attacker with file upload permissions to submit a maliciously crafted ZIP bomb. A ZIP bomb is a compressed archive designed to decompress into an extremely large amount of data, consuming excessive CPU, memory, and disk resources during extraction. This can lead to resource exhaustion on the server, causing performance degradation or denial of service (DoS). Furthermore, if no subsequent file uploads occur to trigger the cleanup process, the extracted data may persist on disk, occupying significant storage space and potentially rendering the system unavailable due to lack of disk space. The vulnerability does not impact confidentiality or integrity, as it does not allow arbitrary code execution or data tampering, but it severely impacts availability. Exploitation requires the attacker to have permission to upload files, which implies some level of authentication or authorization. No user interaction beyond the upload is necessary. The CVSS v3.1 base score is 6.5 (medium severity), reflecting the network attack vector, low attack complexity, required privileges, no user interaction, unchanged scope, no confidentiality or integrity impact, and high availability impact. No patches or exploit code are currently known. The CWE classification is CWE-409 (Improper Management of Critical State Data).

For European organizations, the primary impact of CVE-2025-63914 is a denial of service condition caused by resource exhaustion during ZIP file extraction. This can disrupt business operations, especially for services relying on file uploads and automated processing. Organizations handling large volumes of user-generated content or internal file transfers using Cinnamon kotaemon are at risk of service outages or degraded performance. The persistence of extracted data occupying disk space can exacerbate availability issues, potentially leading to system crashes or inability to process further requests. While confidentiality and integrity remain unaffected, the availability impact can affect customer trust, regulatory compliance (e.g., GDPR mandates on service availability), and operational continuity. Attackers with upload permissions, such as internal users or authenticated external users, could exploit this vulnerability to disrupt services. This risk is heightened in environments where file upload controls are lax or where automated cleanup mechanisms are not enforced. The absence of known exploits in the wild reduces immediate risk but does not eliminate potential future attacks.

To mitigate CVE-2025-63914, European organizations should implement several targeted controls beyond generic advice: 1) Enforce strict validation of ZIP file contents before extraction, including limiting the number of files, maximum decompressed size, and file types allowed. 2) Implement resource usage limits during decompression, such as CPU time, memory allocation, and disk space quotas, to prevent resource exhaustion. 3) Ensure that the temporary extraction directory is reliably and promptly cleaned after each extraction, even if no subsequent uploads occur, to avoid disk space accumulation. 4) Restrict file upload permissions to trusted users and implement strong authentication and authorization controls. 5) Monitor system resource usage and disk space to detect abnormal spikes indicative of ZIP bomb attacks. 6) Consider using sandboxed or isolated environments for file extraction to contain potential impacts. 7) Stay updated with vendor patches or security advisories for Cinnamon kotaemon and apply them promptly once available. 8) Educate administrators and users about the risks of uploading untrusted archives and enforce organizational policies accordingly.