1.1.1d is fixed if you patch that part of the code. The version going from "+deb10u4" to "+deb10u6" indicates that there are supplementary changes that the Deb

1.1.1d is fixed if you patch that part of the code. The version going from "+deb10u4" to "+deb10u6" indicates that there are supplementary changes that the Debian project made on top of the vendor release of 1.1.1d. Going from 1.1.1d to e, f, g, h, i, or j may introduce other behaviour changes that could be undesirable, so Debian 10 (in this example) is frozen using 1.1.1d and any bugs are dealt with on an as-needed basis.