CVE-2025-46206 is a denial of service (DoS) vulnerability found in Artifex MuPDF versions 1.25.5 and 1.25.6, specifically affecting the `mutool clean` utility. The vulnerability arises due to an infinite recursion condition triggered by processing a crafted PDF file containing cyclic /Next references within the outline structure. The function `strip_outline()` is responsible for traversing the PDF outline tree, but when it encounters cyclic references, it enters an infinite recursion loop, exhausting system resources and causing the utility to hang or crash. This vulnerability can be exploited remotely by an attacker who can supply a malicious PDF file to a system running the vulnerable version of MuPDF's `mutool clean`. Since the attack vector involves crafted PDF files, any system or application that uses `mutool clean` to sanitize or process PDFs is potentially at risk. The vulnerability does not require authentication or user interaction beyond opening or processing the malicious PDF file with the affected utility. No known exploits are currently reported in the wild, and no patches or fixes have been linked yet. The lack of a CVSS score indicates that the vulnerability is newly disclosed and may not have undergone full severity assessment. However, the technical details confirm a resource exhaustion condition that can disrupt availability of services relying on MuPDF's processing capabilities.

For European organizations, the primary impact of CVE-2025-46206 is the potential disruption of services that rely on MuPDF's `mutool clean` utility for PDF processing, sanitization, or conversion. This includes document management systems, automated PDF workflows, and security tools that use MuPDF to handle PDF files. A successful exploitation leads to denial of service, which can cause application crashes, service downtime, or resource exhaustion on critical systems. This may affect business continuity, especially in sectors heavily reliant on document processing such as legal, finance, government, and publishing. Additionally, organizations that automatically process user-submitted PDFs (e.g., web portals, email gateways) may be vulnerable to remote DoS attacks if they incorporate the vulnerable MuPDF versions. While the vulnerability does not directly lead to data breach or code execution, the availability impact can disrupt operations and potentially cause cascading effects if critical systems become unresponsive. The absence of known exploits reduces immediate risk, but the ease of triggering infinite recursion with crafted PDFs means attackers could develop exploits quickly once the vulnerability is publicized.

European organizations should take the following specific mitigation steps: 1) Identify and inventory all systems and applications using MuPDF, particularly versions 1.25.5 and 1.25.6, and specifically those utilizing the `mutool clean` utility. 2) Monitor official Artifex communications and security advisories for patches or updates addressing this vulnerability and apply them promptly once available. 3) Implement input validation and filtering at the perimeter to block or quarantine suspicious PDF files, especially those with complex or unusual outline structures. 4) Where possible, isolate PDF processing workflows in sandboxed or containerized environments to limit the impact of potential DoS conditions. 5) Employ resource limits and timeouts on PDF processing utilities to prevent infinite recursion from exhausting system resources. 6) Consider alternative PDF processing tools that are not affected by this vulnerability until a patch is released. 7) Educate security and IT teams about the risk of malicious PDFs causing service disruption and encourage vigilance in monitoring logs and system behavior for signs of exploitation attempts.