I have. From the FAQ (https://backports.debian.org/FAQ/ https://backports.debian.org/FAQ/): "Q: Is there security support for packages from backports.debian.o

I have. From the FAQ (https://backports.debian.org/FAQ/ https://backports.debian.org/FAQ/): "Q: Is there security support for packages from backports.debian.org?" "A: Unfortunately not. [...]"