Add SECURITY policy

Author: zanieb

SECURITY.md

@@ -0,0 +1,18 @@
+# Security Policy
+
+## Scope of security vulnerabilities
+
+uv is a Python package manager. Due to the design of the Python and its packaging ecosystem, there
+are many cases where uv can execute arbitrary code. For example:
+
+- uv invokes Python interpreters on the system to retrieve metadata
+- uv builds source distributions as described by PEP 517
+- uv may build packages from the requested package indexes
+
+These are not considered vulnerabilities in uv. If you think uv's stance in these areas can be
+hardened, please file an issue for a new feature.
+
+## Reporting a vulnerability
+
+If you have found a possible vulnerability that is not excluded by the above
+[scope](#scope-of-security-vulnerabilities), please email `security at astral dot sh`.