CVE-2025-62708 is a vulnerability identified in the py-pdf pypdf library, a widely used open-source pure-Python PDF processing tool. The flaw arises from improper handling of highly compressed data streams within PDF files, specifically when parsing content streams that use the LZWDecode filter. An attacker can craft a malicious PDF file that exploits this weakness by embedding highly compressed data designed to cause excessive memory allocation during decompression. This leads to data amplification and large memory consumption, potentially exhausting system resources and causing denial of service (DoS) conditions. The vulnerability affects all pypdf versions prior to 6.1.3 and does not require any authentication or user interaction to be exploited, as the attack vector is simply the processing of a malicious PDF file. The CVSS 4.0 base score is 6.6 (medium severity), reflecting the network attack vector, low attack complexity, no privileges or user interaction needed, and a high impact on availability. The vulnerability has been publicly disclosed and fixed in version 6.1.3 of pypdf. No known exploits are currently reported in the wild. The root cause is classified under CWE-409, which relates to improper handling of highly compressed data leading to resource exhaustion. This vulnerability is particularly relevant for applications and services that automatically parse or analyze PDF files using vulnerable pypdf versions, especially when processing untrusted or user-submitted documents.

The primary impact of CVE-2025-62708 is denial of service through resource exhaustion, specifically large memory consumption during PDF parsing. For European organizations, this can disrupt critical business processes that rely on automated PDF processing, such as document management systems, e-invoicing platforms, and content management workflows. Organizations in sectors like finance, legal, healthcare, and government, which frequently handle large volumes of PDF documents, may experience service outages or degraded performance if vulnerable pypdf versions are used. The vulnerability could be exploited remotely by submitting malicious PDFs, potentially causing application crashes or system instability. While the vulnerability does not directly compromise confidentiality or integrity, the availability impact can lead to operational downtime and associated financial and reputational damage. Additionally, denial of service conditions could be leveraged as part of multi-stage attacks or to distract security teams. The lack of known exploits in the wild suggests limited current exploitation, but the ease of exploitation and network vector mean the risk could increase if weaponized. European organizations using pypdf in web services, cloud environments, or internal tools should be particularly vigilant.

1. Immediately upgrade all instances of pypdf to version 6.1.3 or later, which contains the fix for this vulnerability. 2. Implement strict input validation and filtering to block or quarantine suspicious PDF files, especially those with unusual compression or encoding characteristics. 3. Enforce resource limits (memory and CPU) on PDF processing components to prevent excessive resource consumption from malformed files. 4. Use sandboxing or isolated environments for PDF parsing to contain potential denial of service impacts. 5. Monitor application logs and system metrics for abnormal memory usage or crashes related to PDF processing. 6. Educate developers and system administrators about this vulnerability and ensure secure coding practices when handling untrusted documents. 7. If upgrading immediately is not feasible, consider disabling or restricting the use of the LZWDecode filter in PDF processing workflows as a temporary workaround. 8. Regularly review and update third-party libraries to incorporate security patches promptly. 9. Conduct security testing with crafted PDFs to verify resilience against resource exhaustion attacks. 10. Maintain an incident response plan to quickly address potential denial of service incidents stemming from PDF processing.