CVE-2025-27931 is a medium-severity vulnerability classified as CWE-125 (Out-of-bounds Read) found in PDF-XChange Editor version 10.5.2.395, specifically within its Enhanced Metafile (EMF) processing functionality. The vulnerability arises when the application processes a specially crafted EMF file, causing it to read memory outside the intended buffer boundaries. This out-of-bounds read can lead to the exposure of sensitive information residing in adjacent memory areas, potentially leaking confidential data to an attacker. The attack vector is remote network (AV:N) with low attack complexity (AC:L), requiring no privileges (PR:N) but does require user interaction (UI:R) to open the malicious file. The scope is unchanged (S:U), meaning the vulnerability affects only the vulnerable component without impacting other system components. The confidentiality impact is high (C:H), while integrity and availability impacts are none (I:N, A:N). No patches were available at the time of disclosure, and no known exploits have been reported in the wild. The vulnerability highlights risks in handling complex file formats like EMF within document editors, emphasizing the need for robust input validation and memory safety. PDF-XChange Editor is widely used in various sectors for document viewing and editing, making this vulnerability relevant for organizations processing untrusted or external PDF and EMF content.

For European organizations, this vulnerability poses a risk of sensitive information disclosure if users open malicious EMF files embedded or linked within PDFs or other documents. Sectors such as finance, legal, government, and healthcare, which frequently handle confidential documents, could be targeted to leak intellectual property, personal data, or classified information. The medium severity and requirement for user interaction reduce the likelihood of widespread automated exploitation but do not eliminate targeted phishing or social engineering attacks. The absence of integrity or availability impact means the vulnerability does not allow attackers to modify data or disrupt services directly, but the confidentiality breach alone can have serious regulatory and reputational consequences under GDPR and other data protection laws. Organizations relying on PDF-XChange Editor version 10.5.2.395 without mitigations are vulnerable to data leakage, especially if EMF files are received from untrusted sources or external collaborators.

1. Immediately restrict or disable the opening of EMF files within PDF-XChange Editor until a vendor patch is released. 2. Implement strict email and file filtering to block or quarantine documents containing embedded EMF files from untrusted sources. 3. Educate users about the risks of opening unexpected or suspicious PDF documents, emphasizing caution with embedded graphics or attachments. 4. Use application sandboxing or containerization to isolate PDF-XChange Editor processes, limiting potential data exposure. 5. Monitor for updates from PDF-XChange Co. Ltd and apply patches promptly once available. 6. Employ endpoint detection and response (EDR) tools to detect anomalous behavior related to document processing. 7. Consider alternative PDF viewers with a better security track record if immediate patching is not feasible. 8. Conduct regular security awareness training focusing on phishing and social engineering tactics that could deliver malicious documents.