CVE-2025-43718 is a vulnerability affecting Poppler versions from 24.06.1 through any 25.x versions prior to 25.04.0. Poppler is a widely used open-source PDF rendering library utilized by many applications and systems to process PDF documents. The vulnerability arises due to excessive stack consumption leading to a segmentation fault (SIGSEGV) caused by deeply nested structures within the metadata of a PDF document. Specifically, the issue occurs in the handling of metadata fields such as GTS_PDFEVersion, where a crafted PDF can include a deeply nested or excessively long regular expression pattern (e.g., a long pdfsubver string). The flaw is triggered in the functions Dict::lookup, Catalog::getMetadata, and related PDFDoc methods, which perform recursive lookups and regex executions. The recursion depth in the regex executor (std::__detail::_Executor) can cause stack exhaustion, resulting in a crash of the application processing the PDF. This is a denial-of-service (DoS) type vulnerability that can be exploited by an attacker supplying a maliciously crafted PDF document to cause a crash in any software relying on the vulnerable Poppler library versions. No known exploits are reported in the wild as of the publication date. No CVSS score has been assigned yet, and no patches or fixes are linked in the provided information, though the vulnerability is marked as published and reserved in the CVE database.

For European organizations, the impact of CVE-2025-43718 primarily concerns availability and reliability of systems that process PDF files using vulnerable Poppler versions. Many Linux distributions, open-source projects, and commercial products incorporate Poppler for PDF rendering, including document viewers, email clients, and web browsers. An attacker could exploit this vulnerability by sending or embedding a malicious PDF in emails, websites, or document repositories, causing targeted applications to crash or become unresponsive. This could disrupt business operations, cause denial of service to users, and potentially be used as part of a larger attack chain to degrade system stability. While this vulnerability does not directly lead to code execution or data leakage, the induced crashes could be leveraged to interrupt critical workflows, especially in sectors heavily reliant on document processing such as finance, legal, government, and media. Additionally, repeated exploitation could lead to resource exhaustion on servers handling PDF processing at scale. The lack of known exploits reduces immediate risk, but the widespread use of Poppler in European IT environments means the vulnerability should be taken seriously to prevent potential service disruptions.

European organizations should take the following specific steps to mitigate CVE-2025-43718: 1) Identify all systems and applications using Poppler versions 24.06.1 through any 25.x prior to 25.04.0, including indirect dependencies in software stacks. 2) Monitor vendor and open-source project announcements for patches or updated Poppler releases addressing this vulnerability and apply them promptly once available. 3) Implement input validation and filtering on PDF files received from untrusted sources, such as email gateways and web application firewalls, to detect and block PDFs with suspiciously deep metadata structures or excessively long regex patterns. 4) Employ sandboxing or process isolation for PDF rendering components to contain crashes and prevent cascading failures in critical systems. 5) Increase logging and monitoring of PDF processing failures to detect potential exploitation attempts early. 6) Where possible, restrict or disable automatic PDF rendering in email clients or web browsers for untrusted content until patches are applied. 7) Educate users and administrators about the risks of opening PDFs from unknown or untrusted sources. These targeted mitigations go beyond generic advice by focusing on the specific nature of the vulnerability (deep recursion in metadata regex processing) and the typical deployment scenarios of Poppler in European IT environments.