As of the publication of this article, Cisco has released several PSIRTs (Product Security Incident Response Team) alerts affecting the 15.7M train.
The fans on the 3900 surged to a roar. The status lights flickered from green to amber. For three minutes, the regional hub was dark. Then, the console text began to scroll: Self-extracting the image... [OK] C3900-universalk9-mz.spa.157-3.m8.bin
Fixed unexpected reloads triggered by IOS Zone-based Firewall configurations. As of the publication of this article, Cisco
: Keep running it if it works, but plan hardware migration. Recommendation for new projects : Use ISR 4000 series with IOS XE 17.x. For three minutes, the regional hub was dark
Because this is a universalk9 image, licensing determines which feature set level is active. After booting the image, you can activate one of three technology packages using Cisco Software Activation (right-to-use or permanent licenses):