CVE-2019-25634: 4mhz BASE64 Decoder

High severity, CVSS 7.8. EPSS: 0.3% chance of exploitation in the next 30 days.

Base64 Decoder 1.1.2 contains a stack-based buffer overflow vulnerability that allows local attackers to execute arbitrary code by triggering a structured exception handler (SEH) overwrite. Attackers can craft a malicious input file that overflows a buffer, overwrites the SEH chain with a POP-POP-RET gadget address, and uses an egghunter payload to locate and execute shellcode for code execution.

Affected products

• 4mhz BASE64 Decoder: version 1.1.2 only

Published 2026-03-24. Last modified 2026-06-17.