Foxit PDF Reader Use-After-Free Flaw Could Leak Sensitive Memory Data
A use-after-free vulnerability in Foxit PDF Reader's handling of AcroForm Signature objects could allow attackers to leak sensitive memory contents by tricking users into opening a malicious PDF file.
Foxit PDF Reader has been found vulnerable to a use-after-free information disclosure flaw, tracked as CVE-2026-5942, in the way it handles AcroForm Signature objects. The vulnerability, disclosed publicly on April 27, 2026, by the Zero Day Initiative (ZDI-26-303), allows remote attackers to disclose sensitive information from the affected system's memory. User interaction is required, meaning the target must open a malicious PDF file or visit a malicious page for the exploit to succeed.
The specific flaw lies in the lack of validation of the existence of an object prior to performing operations on it. This use-after-free condition occurs when Foxit PDF Reader attempts to access memory that has already been freed, potentially exposing heap memory contents. While the vulnerability alone has a CVSS score of 3.3 (low severity, local attack vector, requiring user interaction), the ZDI advisory notes that attackers could leverage this flaw in conjunction with other vulnerabilities to execute arbitrary code in the context of the current process.
Foxit Software has acknowledged the vulnerability and has issued a security update to correct the issue. Users are urged to update to the latest version of Foxit PDF Reader available from the company's security bulletins page. The vendor received the vulnerability report on March 30, 2026, and the coordinated public advisory was released on April 27, 2026, following standard disclosure timelines.
The vulnerability was reported by an anonymous researcher through the ZDI vulnerability disclosure program. This marks another instance of a memory corruption flaw in PDF parsing software, which remains a common attack vector for targeted intrusions and initial access. While not yet known to be exploited in the wild, the availability of a detailed advisory could prompt threat actors to develop a working exploit.
Enterprises that rely on Foxit PDF Reader should prioritize applying the update, especially if the software is used in environments where users frequently open PDFs from untrusted sources. Organizations are also advised to consider enabling additional protections such as disabling JavaScript in PDF readers and using application sandboxing to mitigate potential exploitation chains that could escalate this information disclosure into a full code execution scenario.
This disclosure adds to the growing number of documented vulnerabilities in widely used PDF reader software, highlighting the persistent risk of memory safety issues in applications that parse complex document formats. The ZDI advisory provides no indication that a public exploit exists, but the technical details disclosed are sufficient for security researchers to independently verify the flaw and potentially develop proof-of-concept code.