CVE-2025-55311 is a vulnerability discovered in Foxit PDF and Editor for Windows and macOS versions prior to 13.2 and 2025 before 2025.2. The flaw arises from the application's handling of JavaScript within PDF files, specifically allowing a crafted PDF to alter annotation content dynamically. By leveraging JavaScript interfaces, an attacker can modify annotations and then clear the file's modification status flag, which is normally used to indicate changes to the document after signing. This effectively circumvents the digital signature verification process, as the signature validation mechanism relies on the modification status to detect tampering. Consequently, an attacker can present a signed PDF that appears unaltered, misleading users about the document's integrity and authenticity. The vulnerability is classified under CWE-347, which relates to improper verification of cryptographic signatures. The CVSS v3.1 base score is 6.5 (medium), reflecting that the attack vector is network-based, requires no privileges, but does require user interaction (opening the malicious PDF). The impact is primarily on integrity, with no direct confidentiality or availability consequences. No public exploits have been reported yet, but the potential for misuse in document fraud or misinformation is significant. The vulnerability affects widely used Foxit PDF products, which are popular alternatives to Adobe Acrobat, especially in corporate and governmental environments.

For European organizations, this vulnerability poses a significant risk to the integrity of digitally signed documents, which are commonly used in legal, financial, and governmental transactions. The ability to alter annotations and clear modification flags can enable attackers to forge or manipulate contracts, official communications, or compliance documents without detection. This undermines trust in digital signatures and could lead to financial losses, legal disputes, and reputational damage. Sectors such as banking, insurance, legal services, and public administration are particularly vulnerable due to their reliance on signed PDFs for critical workflows. Additionally, the widespread use of Foxit PDF in Europe, especially in medium to large enterprises seeking cost-effective PDF solutions, increases the attack surface. Although no confidentiality or availability impacts are noted, the integrity compromise alone can have cascading effects on business processes and regulatory compliance, especially under GDPR and eIDAS frameworks that emphasize data and document integrity.

Organizations should prioritize updating Foxit PDF and Editor to versions 13.2 or later for Windows and 2025.2 or later for macOS once patches are released. Until patches are available, disabling or restricting JavaScript execution within PDFs in Foxit settings can reduce the attack surface. Implementing strict email filtering and sandboxing for PDF attachments can help prevent malicious PDFs from reaching end users. Training users to recognize suspicious PDFs and avoid opening untrusted documents is critical. Additionally, organizations should consider deploying document integrity verification tools that do not solely rely on the application's modification status flag but perform cryptographic validation of signatures independently. Regular audits of signed documents and establishing multi-factor verification for critical document approvals can further mitigate risks. Finally, monitoring for unusual document modification patterns and integrating endpoint detection solutions that flag suspicious PDF behaviors can enhance detection capabilities.