diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0f1b869..0d61464 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,8 +16,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
-      - uses: actions/setup-java@v5
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: actions/setup-java@be666c2fcd27ec809703dec50e508c2fdc7f6654 # v5
         with:
           distribution: "temurin"
           java-version: "18"
diff --git a/.github/workflows/pr_title.yml b/.github/workflows/pr_title.yml
index fb72636..57c7eed 100644
--- a/.github/workflows/pr_title.yml
+++ b/.github/workflows/pr_title.yml
@@ -17,7 +17,7 @@ jobs:
     steps:
       # Please look up the latest version from
       # https://github.com/amannn/action-semantic-pull-request/releases
-      - uses: amannn/action-semantic-pull-request@v6
+      - uses: amannn/action-semantic-pull-request@48f256284bd46cdaab1048c3721360e808335d50 # v6
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 6a26a38..2175e77 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -13,8 +13,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
-      - uses: actions/setup-java@v5
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: actions/setup-java@be666c2fcd27ec809703dec50e508c2fdc7f6654 # v5
         with:
           distribution: "temurin"
           java-version: "18"
diff --git a/.github/workflows/regen.yml b/.github/workflows/regen.yml
index bf7fdb2..e39cf95 100644
--- a/.github/workflows/regen.yml
+++ b/.github/workflows/regen.yml
@@ -13,8 +13,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
-      - uses: actions/setup-java@v5
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: actions/setup-java@be666c2fcd27ec809703dec50e508c2fdc7f6654 # v5
         with:
           distribution: "temurin"
           java-version: "18"
@@ -26,7 +26,7 @@ jobs:
           make clone-proto
           make gen-proto
       - name: Create Pull Request
-        uses: peter-evans/create-pull-request@v8
+        uses: peter-evans/create-pull-request@c0f553fe549906ede9cf27b5156039d195d2ece0 # v8
         with:
           # required so the PR triggers workflow runs
           token: ${{ secrets.GH_CQ_BOT }}
diff --git a/.github/workflows/release_pr.yml b/.github/workflows/release_pr.yml
index 5cbe3ae..2df9788 100644
--- a/.github/workflows/release_pr.yml
+++ b/.github/workflows/release_pr.yml
@@ -11,7 +11,7 @@ jobs:
   release-please:
     runs-on: ubuntu-latest
     steps:
-      - uses: google-github-actions/release-please-action@v4
+      - uses: google-github-actions/release-please-action@e4dc86ba9405554aeba3c6bb2d169500e7d3b4ee # v4
         id: release
         with:
           token: ${{ secrets.GH_CQ_BOT }}