CVE-2019-25689: HTML5 Video Player Buffer Overflow Flaw

CVE-2019-25689 Overview

CVE-2019-25689 is a local buffer overflow vulnerability affecting HTML5 Video Player version 1.2.5. This vulnerability allows attackers to execute arbitrary code by supplying an oversized key code string in the application's registration dialog. The flaw is classified as CWE-787 (Out-of-bounds Write), representing a critical memory corruption issue that can lead to complete system compromise when exploited.

Critical Impact

Successful exploitation allows local attackers to execute arbitrary code with the privileges of the application user, potentially leading to full system compromise through crafted input exceeding the expected buffer size.

Affected Products

• HTML5 Video Player version 1.2.5
• Earlier versions may also be affected

Discovery Timeline

• 2026-04-12 - CVE-2019-25689 published to NVD
• 2026-04-13 - Last updated in NVD database

Technical Details for CVE-2019-25689

Vulnerability Analysis

This buffer overflow vulnerability exists in the Help Register dialog of HTML5 Video Player 1.2.5. The application fails to properly validate the length of user-supplied input in the KEY CODE field before copying it to a fixed-size memory buffer. When input exceeding 997 bytes is supplied, the application writes beyond the allocated buffer boundaries, corrupting adjacent memory regions including potentially critical control structures such as the return address on the stack.

The vulnerability is a non-SEH (Structured Exception Handler) buffer overflow, meaning exploitation does not require overwriting SEH chains. Instead, attackers can directly overwrite the instruction pointer through stack-based buffer corruption, simplifying the exploitation process.

Root Cause

The root cause is improper input validation in the registration key processing function. The application allocates a fixed-size buffer on the stack to store the registration key but does not perform adequate bounds checking before copying user input. This allows attackers to overflow the buffer with carefully crafted input, leading to memory corruption and ultimately arbitrary code execution.

Attack Vector

The attack requires local access to the system where HTML5 Video Player is installed. An attacker must craft a malicious payload exceeding 997 bytes and paste it into the KEY CODE field within the Help Register dialog. When submitted, the oversized input triggers the buffer overflow condition, allowing the attacker to overwrite critical memory structures and redirect execution flow to attacker-controlled shellcode. Proof-of-concept demonstrations have shown the ability to spawn a calculator process, demonstrating arbitrary code execution capability.

Technical details and exploitation techniques are documented in the Exploit-DB #46279 entry and the VulnCheck Security Advisory.

Detection Methods for CVE-2019-25689

Indicators of Compromise

• Presence of HTML5 Video Player version 1.2.5 installed on endpoints
• Abnormal process spawning from the HTML5 Video Player application (e.g., cmd.exe, calc.exe, or unexpected child processes)
• Application crashes or unexpected termination of the HTML5 Video Player process
• Memory access violation logs related to the application

Detection Strategies

• Monitor for unusual process creation chains where HTML5 Video Player spawns unexpected child processes
• Implement application whitelisting to detect and block unauthorized code execution attempts
• Deploy endpoint detection and response (EDR) solutions capable of identifying buffer overflow exploitation patterns
• Review system event logs for application crashes or access violation errors

Monitoring Recommendations

• Enable detailed logging for application execution and process creation events
• Configure SIEM rules to alert on suspicious process hierarchies involving media player applications
• Implement memory protection monitoring to detect exploitation attempts
• Regularly audit installed software versions to identify vulnerable installations

How to Mitigate CVE-2019-25689

Immediate Actions Required

• Remove or disable HTML5 Video Player version 1.2.5 from affected systems
• Consider using alternative video player applications that are actively maintained
• Implement application control policies to restrict execution of vulnerable software
• Apply principle of least privilege to limit the impact of potential exploitation

Patch Information

No vendor patch information is currently available for this vulnerability. The software is distributed through the HTML5 Video Player Download page. Users should check for updated versions or consider migrating to actively supported alternatives.

Workarounds

• Uninstall HTML5 Video Player 1.2.5 from systems until a patched version is available
• Restrict local user access to prevent untrusted users from interacting with the application
• Deploy Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) at the system level to increase exploitation difficulty
• Use application sandboxing solutions to contain potential exploitation attempts

# Windows: Check for installed HTML5 Video Player version
wmic product where "name like '%HTML5 Video Player%'" get name, version

# Consider removing vulnerable installation
wmic product where "name like '%HTML5 Video Player%'" call uninstall /nointeractive