Today Nomad 0.12.7, Nomad 0.11.6, and Nomad 0.10.7 were released to fix a regression caused by the recent security patch.
If the artifact.destination or template.destination field is an absolute path, the path is not appended to the task working directory before testing that it escapes the file sandbox. This breaks the use of interpolating the NOMAD_SECRETS_DIR, NOMAD_TASK_DIR, and NOMAD_ALLOC_DIR variables as part of the destination path.
The regression impacts 0.12.6, 0.11.5, and 0.10.6 and is fixed in 0.12.7, 0.11.6, and 0.10.7.
Binaries - https://releases.hashicorp.com/nomad/0.12.7/
The Nomad Team