diff --git a/.github/workflows/reusable-trivy.yml b/.github/workflows/reusable-trivy.yml
index 11d50c2..8e5ee8d 100644
--- a/.github/workflows/reusable-trivy.yml
+++ b/.github/workflows/reusable-trivy.yml
@@ -111,6 +111,19 @@ jobs:
       actions: read
       packages: read
     steps:
+      # image-ref is scanned by digest from the registry (not a local
+      # docker/containerd/podman image), so Trivy needs an authenticated
+      # pull — without this, all four of its image-source backends fail,
+      # including the remote one ("UNAUTHORIZED: authentication required"),
+      # even for a public GHCR package. Matches sign-and-attest.yml's
+      # identical login step for the same registry.
+      - name: Log in to GHCR
+        uses: docker/login-action@650006c6eb7dba73a995cc03b0b2d7f5ca915bee  # v4.2.0
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Trivy image vulnerability scan
         uses: aquasecurity/trivy-action@ed142fd0673e97e23eac54620cfb913e5ce36c25 # v0.36.0
         with: