Jinja 2.10.1 has been released and includes a security-related fix. If you are using the Jinja sandboxed environment you are encouraged to upgrade.
MITRE has assigned CVE-2019-10906 to this issue.
The sandbox is used to restrict what code can be evaluated when
rendering untrusted, user-provided templates. Due to the way string
formatting works in Python, the
str.format_map method could be used to
escape the sandbox.
This issue was previously addressed for the
str.format method in
Jinja 2.8.1, which discusses the issue in detail. However, the
str.format_map method was overlooked. This release applies
the same sandboxing to both methods.
If you cannot upgrade Jinja, you can override the
method on the sandbox and explicitly disallow the
method on string objects.
If you think you have discovered a security issue in Jinja or another of the Pallets projects, please email firstname.lastname@example.org with details.