CVE-2025-55311 is a security vulnerability identified in Foxit PDF and Editor software for Windows and macOS platforms, affecting versions prior to 13.2 and 2025 before 2025.2. The flaw arises from the software's handling of JavaScript embedded within PDF files, which can be exploited by a crafted PDF document to alter annotation content dynamically. More critically, the JavaScript interface can be used to clear the file's modification status flag, which is normally used to indicate whether a document has been altered after signing. This manipulation effectively circumvents the digital signature verification process, misleading users and automated systems into believing the document remains unmodified and trustworthy. The vulnerability undermines the integrity and non-repudiation guarantees of digitally signed PDFs, which are widely used in legal, financial, and governmental workflows. Although no public exploits have been reported yet, the attack vector requires only that a user opens a malicious PDF, with no authentication or elevated privileges needed. The vulnerability exploits the trust model of digital signatures by hiding unauthorized changes, potentially enabling fraud, misinformation, or unauthorized document alterations. The lack of a CVSS score indicates that the vulnerability has not yet been fully assessed, but the technical details suggest a significant risk to document integrity and trust.

For European organizations, the impact of CVE-2025-55311 is substantial, especially for sectors relying heavily on digitally signed PDF documents such as legal firms, financial institutions, government agencies, and healthcare providers. The ability to alter signed documents without detection can lead to fraudulent contracts, altered financial statements, or tampered official records, undermining trust and potentially causing legal and financial repercussions. The vulnerability threatens confidentiality indirectly by enabling misinformation and integrity directly by allowing undetected document modifications. Availability is less impacted, but operational trust in document workflows may degrade. European organizations that use Foxit PDF products extensively for document signing and verification are at risk of targeted attacks exploiting this vulnerability. The threat could facilitate advanced social engineering or insider attacks, where malicious actors distribute tampered signed documents to deceive recipients. The absence of known exploits in the wild currently reduces immediate risk but does not diminish the urgency of mitigation given the potential impact.

1. Apply patches and updates from Foxit as soon as they become available to address this vulnerability. 2. Temporarily disable JavaScript execution in Foxit PDF and Editor settings to prevent malicious scripts from running within PDFs. 3. Implement strict document validation policies that include secondary verification methods for signed PDFs, such as out-of-band confirmation or cryptographic timestamping. 4. Educate users to be cautious when opening PDFs from untrusted sources, especially those that request enabling JavaScript or contain annotations. 5. Use alternative PDF readers with robust security controls and less reliance on JavaScript for critical document workflows. 6. Employ digital signature verification tools that independently validate document integrity outside of the PDF reader environment. 7. Monitor and audit document signing and modification logs to detect suspicious activities. 8. Consider network-level protections such as sandboxing PDF files before delivery to end users to detect malicious behavior.