The tag is present in Lintian version 2.109.24. That is the most recent version we know about.
The changelog entry references a temporary security identifier, like "TEMP-0000000-2FC21E".
The TEMP identifier will disappear in the future once a proper CVE identifier has been assigned. Therefore it is useless as an external reference. Even worse, the identifier is not stable and may change even before a CVE is allocated.
If a CVE has been allocated, please use that instead. Otherwise, please replace the TEMP identifier with a short description of the issue.