diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b984645..2e03ffb 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -30,6 +30,9 @@ jobs:
         with:
           clients: pip,python,composer,curl,git,npm,cargo
 
+      - name: Disable APT download retries (CVE-2026-109518)
+        run: echo 'Acquire::Retries "0";' | sudo tee /etc/apt/apt.conf.d/99-no-retries >/dev/null
+
       - uses: shivammathur/setup-php@f3e473d116dcccaddc5834248c87452386958240 # v2
         with:
           php-version: '8.3'
diff --git a/.github/workflows/sonar.yml b/.github/workflows/sonar.yml
index fe24358..d6a06f2 100644
--- a/.github/workflows/sonar.yml
+++ b/.github/workflows/sonar.yml
@@ -30,6 +30,8 @@ jobs:
       - uses: durable-workflow/.github/.github/actions/bootstrap-patched-pip@75587fc33ff40c34f32ef777293dad56bb6f48c7 # clean-trust
         with:
           clients: pip,python,composer,curl,git,npm,cargo
+      - name: Disable APT download retries (CVE-2026-109518)
+        run: echo 'Acquire::Retries "0";' | sudo tee /etc/apt/apt.conf.d/99-no-retries >/dev/null
       - uses: shivammathur/setup-php@f3e473d116dcccaddc5834248c87452386958240 # v2
         with:
           php-version: '8.3'
diff --git a/tests/test_apt_no_retries.py b/tests/test_apt_no_retries.py
new file mode 100644
index 0000000..99c0290
--- /dev/null
+++ b/tests/test_apt_no_retries.py
@@ -0,0 +1,49 @@
+"""Every networked APT path in a workflow job runs with APT retries off.
+
+CVE-2026-109518 (durable-workflow/.github#295): vulnerable APT can follow a
+redirect on a retried package download and install a swapped package as root.
+Writing Acquire::Retries "0" before the first APT-capable step removes that
+precondition. shivammathur/setup-php can run apt-get itself, so it counts.
+"""
+
+from pathlib import Path
+import re
+import unittest
+
+import yaml
+
+ROOT = Path(__file__).resolve().parents[1]
+WORKFLOWS = ROOT / '.github/workflows'
+NO_RETRIES = "echo 'Acquire::Retries \"0\";' | sudo tee /etc/apt/apt.conf.d/99-no-retries"
+APT = re.compile(r'\bapt(?:-get)?\b[^\n]{0,80}\b(?:update|install|upgrade|dist-upgrade)\b|--with-deps|install-deps')
+
+
+def apt_capable(step):
+    return str(step.get('uses', '')).startswith('shivammathur/setup-php@') or bool(APT.search(str(step.get('run') or '')))
+
+
+def unprotected(document):
+    for name, job in (document.get('jobs') or {}).items():
+        for step in job.get('steps') or []:
+            if NO_RETRIES in str(step.get('run') or ''):
+                break
+            if apt_capable(step):
+                yield name, step.get('name') or step.get('uses') or step.get('run')
+                break
+
+
+class AptNoRetriesTest(unittest.TestCase):
+    def test_every_apt_capable_job_disables_retries_first(self):
+        found = []
+        for path in sorted(WORKFLOWS.glob('*.y*ml')):
+            for job, step in unprotected(yaml.safe_load(path.read_text())):
+                found.append(f'{path.name}:{job}: {step}')
+        self.assertEqual([], found)
+
+    def test_checker_refuses_a_late_or_missing_line(self):
+        setup = {'uses': 'shivammathur/setup-php@' + 'a' * 40}
+        line = {'run': NO_RETRIES + ' >/dev/null'}
+        self.assertEqual([], list(unprotected({'jobs': {'ok': {'steps': [line, setup]}}})))
+        self.assertEqual(1, len(list(unprotected({'jobs': {'late': {'steps': [setup, line]}}}))))
+        self.assertEqual(1, len(list(unprotected({'jobs': {'none': {'steps': [{'run': 'sudo apt-get update'}]}}}))))
+        self.assertEqual(1, len(list(unprotected({'jobs': {'deps': {'steps': [{'run': 'npx playwright install --with-deps chromium'}]}}}))))
diff --git a/tests/test_ci_trust.py b/tests/test_ci_trust.py
index c7e6eaf..240dac1 100644
--- a/tests/test_ci_trust.py
+++ b/tests/test_ci_trust.py
@@ -19,7 +19,7 @@
                    test_php_linux_qualification, test_php_linux_qualification_workflow,
                    test_bookworm_apt_source, test_private_pip_runtime,
                    test_php_linux_normalize, test_php_linux_archive_metadata, test_php_linux_alternatives,
-                   test_hosted_runtime_parent)
+                   test_hosted_runtime_parent, test_apt_no_retries)
 
 
 ROOT = Path(__file__).resolve().parents[1]
@@ -39,7 +39,8 @@ def load_tests(loader, standard_tests, pattern):
                    test_php_linux_recipe, test_php_linux_archive, test_setup_php_linux,
                    test_php_linux_qualification, test_php_linux_qualification_workflow,
                    test_bookworm_apt_source, test_private_pip_runtime, test_hosted_runtime_parent,
-                   test_php_linux_normalize, test_php_linux_archive_metadata, test_php_linux_alternatives):
+                   test_php_linux_normalize, test_php_linux_archive_metadata, test_php_linux_alternatives,
+                   test_apt_no_retries):
         standard_tests.addTests(loader.loadTestsFromModule(module))
     return standard_tests