diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2a5675f..d6e5233 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,10 +16,10 @@ jobs:
     runs-on: windows-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v7
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@26b0ec14cb23fa6904739307f278c14f94c95bf1 # v5
         with:
           dotnet-version: 8.0.4xx
 
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 52c1ee4..ad81454 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -18,15 +18,15 @@ jobs:
     runs-on: windows-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v7
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@26b0ec14cb23fa6904739307f278c14f94c95bf1 # v5
         with:
           dotnet-version: 8.0.4xx
 
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@v4
+        uses: github/codeql-action/init@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4
         with:
           languages: csharp
           build-mode: manual
@@ -38,4 +38,4 @@ jobs:
         run: dotnet build ARSVIN.sln -c Release --no-restore
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@v4
+        uses: github/codeql-action/analyze@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4
diff --git a/.github/workflows/pages.yml b/.github/workflows/pages.yml
index 989dac1..db53968 100644
--- a/.github/workflows/pages.yml
+++ b/.github/workflows/pages.yml
@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v7
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
 
       - name: Validate public site
         shell: pwsh
@@ -40,13 +40,13 @@ jobs:
           touch site/.nojekyll
 
       - name: Configure Pages
-        uses: actions/configure-pages@v6
+        uses: actions/configure-pages@45bfe0192ca1faeb007ade9deae92b16b8254a0d # v6
 
       - name: Upload Pages artifact
-        uses: actions/upload-pages-artifact@v5
+        uses: actions/upload-pages-artifact@fc324d3547104276b827a68afc52ff2a11cc49c9 # v5
         with:
           path: site
 
       - name: Deploy
         id: deployment
-        uses: actions/deploy-pages@v5
+        uses: actions/deploy-pages@cd2ce8fcbc39b97be8ca5fce6e763baed58fa128 # v5
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index a31ef38..8e5e9a6 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -48,12 +48,12 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v7
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
         with:
           fetch-depth: 0
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@26b0ec14cb23fa6904739307f278c14f94c95bf1 # v5
         with:
           dotnet-version: 8.0.4xx
           cache: true
@@ -266,7 +266,7 @@ jobs:
           Get-Content (Join-Path $releaseRoot 'SHA256SUMS.txt')
 
       - name: Upload release workflow artifact
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: ${{ steps.version.outputs.artifact_name }}
           path: |
@@ -286,13 +286,13 @@ jobs:
 
     steps:
       - name: Download validated release artifact
-        uses: actions/download-artifact@v8
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8
         with:
           name: ${{ needs.package.outputs.artifact_name }}
           path: artifacts/release
 
       - name: Create GitHub Release
-        uses: softprops/action-gh-release@v3
+        uses: softprops/action-gh-release@718ea10b132b3b2eba29c1007bb80653f286566b # v3.0.1
         with:
           tag_name: ${{ needs.package.outputs.tag_name }}
           target_commitish: ${{ github.sha }}
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7dde80e..bf43120 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,12 +4,17 @@ All notable ARSVIN changes are documented here using a lightweight Keep a Change
 
 ## Unreleased
 
+### Security
+
+- Pinned all GitHub Actions used by CI, CodeQL, Pages, and release workflows to immutable commit SHAs while retaining version comments for maintainability and Dependabot updates.
+
 ### Planned
 
-- Supply-chain pinning for GitHub Actions and installer tooling.
+- Exact-version and integrity pinning for installer tooling.
 - Shared `ARSVIN.Engine` class library extraction.
 - Code coverage and analyzer quality gates.
 - Search-indexable HTML engineering documentation.
+- SBOM and release provenance/attestation.
 
 ## 0.3.0 — 2026-07-11