Earlier in time, iPhone Dev Team has released a new update of RedSn0w v0.9.10b, to fix the problems that have occurred with previous versions, this RedSn0w update comes with MobileSubstrate 0.9.3995.
However to get update of MobileSubstrate 0.9.3995 directly without running RedSn0w you can download direct from this link Mobile Substrate 0.9.3995.
How to Download MobileSubstrate 0.9.3995with Cydia?
Open Cydia, go into the Changes package ==> then refresh your sources.
Now the update will appear then you can install MobileSubstrate 0.9.3995 to your device.