diff --git a/.github/workflows/coding-standards.yml b/.github/workflows/coding-standards.yml
index 6b3b9236d1c68..fbce6b90397e9 100644
--- a/.github/workflows/coding-standards.yml
+++ b/.github/workflows/coding-standards.yml
@@ -78,7 +78,7 @@ jobs:
 
   failed-workflow:
     name: Failed workflow tasks
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     permissions:
       actions: write
     needs: [ phpcs, jshint, slack-notifications ]
diff --git a/.github/workflows/javascript-tests.yml b/.github/workflows/javascript-tests.yml
index d3899a2839fcb..e5cf2c6c870c4 100644
--- a/.github/workflows/javascript-tests.yml
+++ b/.github/workflows/javascript-tests.yml
@@ -67,7 +67,7 @@ jobs:
 
   failed-workflow:
     name: Failed workflow tasks
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     permissions:
       actions: write
     needs: [ slack-notifications ]
diff --git a/.github/workflows/phpunit-tests.yml b/.github/workflows/phpunit-tests.yml
index c4c27df5409e5..80f35e0e4873e 100644
--- a/.github/workflows/phpunit-tests.yml
+++ b/.github/workflows/phpunit-tests.yml
@@ -41,7 +41,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ ubuntu-latest ]
+        os: [ ubuntu-26.04 ]
         php: [ '5.3', '7.3' ]
         split_slow: [ false ]
         multisite: [ false, true ]
@@ -50,60 +50,60 @@ jobs:
         include:
           # Include jobs for PHP 7.3 with memcached.
           - php: '7.3'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: true
             split_slow: false
             multisite: false
           - php: '7.3'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: true
             split_slow: false
             multisite: true
           # Include jobs that require specific versions of PHPUnit.
           - php: '7.0'
             phpunit: '6-php-7.0'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: false
             split_slow: false
             multisite: false
           - php: '7.0'
             phpunit: '6-php-7.0'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: false
             split_slow: false
             multisite: true
           - php: '5.6'
             phpunit: '4-php-5.6'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: false
             split_slow: false
             multisite: false
           - php: '5.6'
             phpunit: '4-php-5.6'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: false
             split_slow: false
             multisite: true
           # Additional "slow" jobs for PHP <= 5.6.
           - php: '5.6'
             phpunit: '4-php-5.6'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: false
             split_slow: true
             multisite: false
           - php: '5.6'
             phpunit: '4-php-5.6'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: false
             split_slow: true
             multisite: true
           - php: '5.3'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: false
             split_slow: true
             multisite: false
           - php: '5.3'
-            os: ubuntu-latest
+            os: ubuntu-26.04
             memcached: false
             split_slow: true
             multisite: true
@@ -134,7 +134,7 @@ jobs:
 
   failed-workflow:
     name: Failed workflow tasks
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     permissions:
       actions: write
     needs: [ test-php, slack-notifications ]
diff --git a/.github/workflows/test-build-processes.yml b/.github/workflows/test-build-processes.yml
index f514614647bbd..dea41619afaca 100644
--- a/.github/workflows/test-build-processes.yml
+++ b/.github/workflows/test-build-processes.yml
@@ -45,11 +45,11 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ ubuntu-latest, windows-latest ]
+        os: [ ubuntu-26.04, windows-2025 ]
         directory: [ 'build' ]
         include:
           # Only prepare artifacts once.
-          - os: ubuntu-latest
+          - os: ubuntu-26.04
             directory: 'build'
             prepare-playground: true
     with:
@@ -100,7 +100,7 @@ jobs:
 
   failed-workflow:
     name: Failed workflow tasks
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     permissions:
       actions: write
     needs: [ slack-notifications ]