CVE-2025-62707 is a vulnerability classified under CWE-834 (Excessive Iteration) affecting the pypdf library, a pure-Python PDF processing tool widely used for reading and manipulating PDF files. Versions prior to 6.1.3 contain a flaw where an attacker can craft a specially designed PDF file that includes an inline image using the DCTDecode filter. When pypdf parses the content stream of such a page, it enters an infinite loop due to excessive iteration over the content stream data. This infinite loop leads to denial of service by causing the consuming application to hang or consume excessive CPU resources, potentially leading to resource exhaustion. The vulnerability does not require any privileges, authentication, or user interaction, making it remotely exploitable simply by processing a malicious PDF. Although no known exploits are reported in the wild, the vulnerability poses a risk to any system that automatically processes untrusted PDF files using vulnerable pypdf versions. The issue was addressed and fixed in pypdf version 6.1.3, which prevents the infinite loop condition during parsing.

For European organizations, the primary impact of this vulnerability is denial of service through resource exhaustion. Organizations that rely on automated PDF processing—such as document management systems, email gateways, web applications, or backend services that parse PDFs—may experience application hangs or crashes when processing malicious PDFs. This can disrupt business operations, delay workflows, and potentially cause cascading failures in dependent systems. Confidentiality and integrity are not directly impacted, but availability degradation can affect critical services. Sectors such as finance, legal, healthcare, and government, which often handle large volumes of PDF documents, may be particularly vulnerable. Additionally, organizations that accept PDFs from external or untrusted sources without validation are at higher risk. The lack of known exploits reduces immediate threat but does not eliminate risk, especially as attackers may develop exploits over time.

The most effective mitigation is to upgrade all instances of pypdf to version 6.1.3 or later, where the infinite loop vulnerability is fixed. Organizations should audit their software dependencies to identify usage of vulnerable pypdf versions. For environments where immediate upgrade is not feasible, implement input validation and filtering to detect and block PDFs containing suspicious inline images with DCTDecode filters. Employ sandboxing or resource-limiting techniques when processing PDFs to prevent excessive CPU or memory consumption. Monitoring and alerting on abnormal resource usage during PDF processing can help detect exploitation attempts. Additionally, restrict PDF processing to trusted sources where possible and apply network-level controls to limit exposure. Regularly review and update PDF processing libraries to incorporate security patches promptly.