I have just released Slim Framework 4.15.3.
Among other fixes, it addresses a route parameter constraint bypass vulnerability in the routing component.
If you are using Slim 4.0.0 to 4.15.2 & use route placeholder values without revalidating them, upgrade.
www.slimframework.com/2026/08/31/s...
slimframework.com
Slim 4.15.3 released
Slim 4.15.3 released