CVE-2019-25550: Encrypt PDF Buffer Overflow Vulnerability

CVE-2019-25550 Overview

CVE-2019-25550 is a buffer overflow vulnerability affecting Encrypt PDF version 2.3, a PDF encryption software developed by VeryPDF. The vulnerability allows local attackers to crash the application by inputting excessively long strings into password fields. Specifically, attackers can paste a 1000-byte buffer into the User Password or Master Password field in the Settings dialog, which triggers an application crash when importing PDF files.

Critical Impact

Local attackers can exploit this buffer overflow vulnerability to cause a denial of service condition, crashing the Encrypt PDF application and potentially disrupting document encryption workflows.

Affected Products

• Encrypt PDF 2.3
• VeryPDF Encrypt PDF software

Discovery Timeline

• 2026-03-21 - CVE CVE-2019-25550 published to NVD
• 2026-03-23 - Last updated in NVD database

Technical Details for CVE-2019-25550

Vulnerability Analysis

This buffer overflow vulnerability (CWE-787: Out-of-bounds Write) exists in Encrypt PDF 2.3's password input handling mechanism. The application fails to properly validate the length of user-supplied input in the password fields within the Settings dialog. When processing the User Password or Master Password fields, the application allocates a fixed-size buffer that is insufficient to handle oversized input strings.

The vulnerability is triggered during the PDF import operation, where the application attempts to process the previously entered password data. The lack of proper bounds checking allows data to overflow the allocated buffer boundaries, corrupting adjacent memory and ultimately causing the application to crash.

Root Cause

The root cause of this vulnerability is inadequate input validation and buffer size management in the password field processing routines. The application does not enforce a maximum character limit on password input fields, nor does it perform boundary checks when copying password data into internal buffers. This classic buffer overflow condition allows attackers to overwrite memory beyond the intended buffer allocation, leading to memory corruption and application instability.

Attack Vector

The attack requires local access to the system where Encrypt PDF 2.3 is installed. An attacker must interact with the application's graphical user interface to exploit this vulnerability. The attack sequence involves:

1. Opening the Encrypt PDF application
2. Navigating to the Settings dialog
3. Pasting a large string (approximately 1000 bytes or more) into either the User Password or Master Password field
4. Attempting to import a PDF file

The application crashes when processing the oversized password input during the PDF import operation. While this vulnerability primarily results in denial of service, buffer overflow conditions can potentially be leveraged for more severe attacks such as code execution if the memory layout is favorable.

Detection Methods for CVE-2019-25550

Indicators of Compromise

• Unexpected crashes of the Encrypt PDF application during PDF import operations
• Application crash logs indicating memory access violations or buffer overrun errors
• Presence of unusually long strings in password-related configuration files or memory dumps

Detection Strategies

• Monitor for repeated Encrypt PDF application crashes that may indicate exploitation attempts
• Implement application crash monitoring and logging to detect patterns consistent with buffer overflow attacks
• Review Windows Event Logs for application error events related to Encrypt PDF 2.3

Monitoring Recommendations

• Deploy endpoint detection and response (EDR) solutions capable of detecting application crashes and memory corruption events
• Establish baseline crash behavior for Encrypt PDF to identify anomalous crash patterns
• Monitor user activity on systems with Encrypt PDF installed for suspicious interaction patterns

How to Mitigate CVE-2019-25550

Immediate Actions Required

• Consider upgrading to a newer version of Encrypt PDF if available from VeryPDF
• Restrict access to systems running Encrypt PDF 2.3 to trusted users only
• Implement application whitelisting and user access controls to limit who can interact with the vulnerable software
• Evaluate alternative PDF encryption solutions if patches are not available

Patch Information

No vendor patch information is currently available for this vulnerability. Users should check the VeryPDF Official Website for any security updates or newer versions of Encrypt PDF that may address this issue. Additional technical details about this vulnerability can be found at the Exploit-DB #46871 entry and the VulnCheck Denial of Service Advisory.

Workarounds

• Limit physical and remote access to systems running Encrypt PDF 2.3 to prevent unauthorized users from exploiting the vulnerability
• Implement clipboard content filtering policies if possible to prevent pasting of excessively long strings
• Use password management policies that enforce reasonable password lengths
• Consider running the application in a sandboxed environment to limit the impact of potential crashes