Why Cisco IOS Release 15.9(3)M10 (c800-universalk9-mz.SPA.159-3.M10.bin) is a Critical Upgrade
: "m" means the image runs from RAM, and "z" means the file is zip-compressed to save space in flash memory. : Stands for Software Production Assembly c800universalk9mzspa1593m10bin better
The universalk9 designation means:
Consolidated Fixes: It includes resolved caveats and security patches (PSIRT advisories) accumulated throughout the 15.9(3)M maintenance train. Why Cisco IOS Release 15
The primary reason 15.9(3)M10 is "better" than its predecessors is the security landscape. This version includes fixes for numerous Common Vulnerabilities and Exposures (CVEs) that affected earlier 15.x releases. This includes: Cisco 860 series (e
Guest OS (GOS): Included in system bundles (e.g., version 1.15.0.8) for hosting IOx applications.