Debian 10 Buster DLA-3744-1 Critical Python-Django Security Advisory

* CVE-2021-28658: Prevent a directory traversal issue which could
have been exploited by maliciously crafted filenames. However, the
built-in upload handlers were not affected by this vulnerability.
(#986447)

* CVE-2021-31542: Fix a potential directory-traversal vulnerability
that could have been exploited by uploaded files. The
MultiPartParser, UploadedFile and FieldFile classes allowed
directory-traversal via uploaded files with suitably crafted file
names. In order to mitigate this risk, stricter basename and path
sanitation is now applied. Specifically, empty file names and
paths with dot segments are rejected. (#988053)

* CVE-2021-33203: Prevent a potential directory traversal via
admindocs. Staff members could use the admindocs
TemplateDetailView view to check the existence of arbitrary files.
Additionally, if (and only if) the default admindocs templates
have been customized by the developers to also expose the file