diff --git a/README.md b/README.md
index cd87d44..3717508 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# `actions/attest-build-provenance`
+#141`actions/attest-build-provenance`
 
 [![Public-Good Sigstore Prober](https://github.com/actions/attest-build-provenance/actions/workflows/prober-public-good.yml/badge.svg)](https://github.com/actions/attest-build-provenance/actions/workflows/prober-public-good.yml)
 [![GitHub Sigstore Prober](https://github.com/actions/attest-build-provenance/actions/workflows/prober-github.yml/badge.svg)](https://github.com/actions/attest-build-provenance/actions/workflows/prober-github.yml)
diff --git a/SECURITY.md b/SECURITY.md
new file mode 100644
index 0000000..034e848
--- /dev/null
+++ b/SECURITY.md
@@ -0,0 +1,21 @@
+# Security Policy
+
+## Supported Versions
+
+Use this section to tell people about which versions of your project are
+currently being supported with security updates.
+
+| Version | Supported          |
+| ------- | ------------------ |
+| 5.1.x   | :white_check_mark: |
+| 5.0.x   | :x:                |
+| 4.0.x   | :white_check_mark: |
+| < 4.0   | :x:                |
+
+## Reporting a Vulnerability
+
+Use this section to tell people how to report a vulnerability.
+
+Tell them where to go, how often they can expect to get an update on a
+reported vulnerability, what to expect if the vulnerability is accepted or
+declined, etc.