diff --git a/.github/workflows/check-test-vectors.yml b/.github/workflows/check-test-vectors.yml
new file mode 100644
index 0000000000..ccf7bf5851
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+++ b/.github/workflows/check-test-vectors.yml
@@ -0,0 +1,69 @@
+name: Check Test Vectors
+on:
+  schedule:
+    # Run weekly on Wednesdays at 10 AM PT (6 PM UTC)
+    - cron: '0 18 * * 3'
+  workflow_dispatch: # Allow manual triggering
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  check-vectors:
+    if: github.repository_owner == 'aws'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install Rust and Cargo
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Install duvet
+        run: cargo install duvet --locked
+
+      - name: Check test vectors are up-to-date
+        id: check_vectors
+        run: |
+          cd third_party/vectors
+          if python3 ./sync.py --check; then
+            echo "vectors_outdated=false" >> $GITHUB_OUTPUT
+            echo "✅ Test vectors are up-to-date"
+          else
+            echo "vectors_outdated=true" >> $GITHUB_OUTPUT
+            echo "❌ Test vectors are outdated"
+          fi
+
+      - name: Create Pull Request for outdated vectors
+        if: steps.check_vectors.outputs.vectors_outdated == 'true'
+        uses: peter-evans/create-pull-request@v8
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          branch: update-third-party-vectors
+          delete-branch: true
+          title: 'Update third-party test vectors'
+          body: |
+            ### Issues:
+            Automated check detected that some third-party test vectors in `third_party/vectors` need to be updated.
+
+            ### Next Steps
+            - Run `cd third_party/vectors && python3 ./sync.py` locally to update vectors
+            - Review any new test vectors that are added
+            - Run `ninja -C build crypto_test` to ensure all tests pass
+            - Run `python3 util/generate_build_files.py` to update build files
+            - Verify `cd third_party/vectors && python3 ./sync.py --check` returns success
+
+            By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.
+          assignees: sgmenda
+          draft: false
+
+      - name: Vectors up-to-date summary
+        if: steps.check_vectors.outputs.vectors_outdated == 'false'
+        run: |
+          echo "✅ Test vectors are up-to-date. No action needed."