The story of the "Adobe Reader 11 patch" is ultimately a story about the lifecycle of software. It had a good run—five years of active support and nearly a decade of existence.
Hackers often target organizations known to use legacy software. If an attacker knows a company is running Windows 7 with Adobe Reader 11, they can craft a specific PDF exploit that is guaranteed to work because the software is defenseless against modern attack signatures. adobe reader 11 patch
Later patches for version 11 addressed serious "out of the wild" exploits and sandbox bypass vulnerabilities that could lead to unauthorized code execution. The story of the "Adobe Reader 11 patch"
Adobe has removed the easy download links from its main landing pages. However, they maintain an FTP archive for enterprise customers. adobe reader 11 patch