CVE-2022-1388 and 4000s
Is it possible to run 13.1.5 on a 4000s box? The hardware/software compatibility matrix indicates that the 4000s caps out at 13.1.3. Is this a hard limit or more of a "upgrade at your own risk"?
Yes, per https://support.f5.com/csp/article/K9476, on a 4000s BIG-IP Standard series platform, the compatible version on 13.x is through 13.1.3. I'm afraid upgrading to 13.1.5 is at your own risk as it will be an unsupported configuration. This is not tested and you may encounter issues depending on your current system configuration.