diff --git a/.github/workflows/strix.yml b/.github/workflows/strix.yml
index 177a31aa..879aab65 100644
--- a/.github/workflows/strix.yml
+++ b/.github/workflows/strix.yml
@@ -485,6 +485,11 @@ jobs:
         working-directory: trusted-strix-source
         run: |
           set -euo pipefail
+          # GitHub-hosted runners may inherit a collaborative umask (0002),
+          # which makes pip-generated console scripts group-writable.  Pin a
+          # private install umask before creating the credential-bearing Strix
+          # entry point; the runtime gate still rejects any later relaxation.
+          umask 022
           python3 -m pip install --disable-pip-version-check --no-cache-dir --require-hashes -r requirements-strix-ci-hashes.txt
           strix_executable="$(command -v strix || true)"
           if [ -z "$strix_executable" ] || [[ "$strix_executable" != /* ]] \
@@ -508,9 +513,11 @@ jobs:
           print(hashlib.sha256(Path(sys.argv[1]).read_bytes()).hexdigest())
           PY
           )"
-          printf 'STRIX_EXECUTABLE_PATH=%s\n' "$strix_executable" >> "$GITHUB_ENV"
-          printf 'STRIX_EXECUTABLE_ROOT=%s\n' "$strix_scripts_root" >> "$GITHUB_ENV"
-          printf 'STRIX_EXECUTABLE_SHA256=%s\n' "$strix_executable_sha256" >> "$GITHUB_ENV"
+          {
+            printf 'STRIX_EXECUTABLE_PATH=%s\n' "$strix_executable"
+            printf 'STRIX_EXECUTABLE_ROOT=%s\n' "$strix_scripts_root"
+            printf 'STRIX_EXECUTABLE_SHA256=%s\n' "$strix_executable_sha256"
+          } >> "$GITHUB_ENV"
 
       - name: Mask LLM API key
         if: steps.gate.outputs.enabled == 'true'
diff --git a/scripts/ci/test_strix_quick_gate.sh b/scripts/ci/test_strix_quick_gate.sh
index a8e62d9d..3a1cb943 100755
--- a/scripts/ci/test_strix_quick_gate.sh
+++ b/scripts/ci/test_strix_quick_gate.sh
@@ -889,6 +889,7 @@ assert_opencode_review_uses_codegraph_and_gpt5_fallback() {
 	assert_file_contains "$REPO_ROOT/.github/workflows/strix.yml" 'STRIX_EXECUTABLE_PATH=%s' "Strix workflow captures the pinned installation executable before scanning"
 	assert_file_contains "$REPO_ROOT/.github/workflows/strix.yml" 'STRIX_EXECUTABLE_SHA256=%s' "Strix workflow pins the installed executable digest before scanning"
 	assert_file_contains "$REPO_ROOT/.github/workflows/strix.yml" 'STRIX_EXECUTABLE_ROOT=%s' "Strix workflow pins the installed executable root before scanning"
+	assert_file_contains "$REPO_ROOT/.github/workflows/strix.yml" 'umask 022' "Strix workflow creates the credential-bearing executable without group/world write access"
 	assert_file_contains "$GATE_SCRIPT" 'STRIX_EXECUTABLE_PATH must name the trusted installed Strix executable' "Strix gate requires an explicit trusted executable path"
 	assert_file_contains "$GATE_SCRIPT" 'did not match the pinned SHA-256 digest' "Strix gate rejects executable substitution after trusted installation"
 	assert_file_contains "$GATE_SCRIPT" 'STRIX_EXECUTABLE_PATH must be outside the untrusted scan target' "Strix executable cannot come from the scan target"
@@ -3184,7 +3185,7 @@ printf '%s\n' "$target_path" >> "${FAKE_STRIX_TARGET_LOG:?}"
 STRIX_REPORTS_DIR="${STRIX_REPORTS_DIR:-strix_runs}"
 
 case "${FAKE_STRIX_SCENARIO:?}" in
-	success|runtime-env-forwarding|vertex-primary-success-timing-message|direct-openai-gpt-does-not-require-github-models-api-base|pr-executable-integrity-mismatch)
+success|runtime-env-forwarding|vertex-primary-success-timing-message|direct-openai-gpt-does-not-require-github-models-api-base|pr-executable-integrity-mismatch|pr-executable-group-writable)
 		echo "scan ok"
 		exit 0
 		;;
@@ -5357,6 +5358,9 @@ PY
 			STRIX_EXECUTABLE_SHA256="0000000000000000000000000000000000000000000000000000000000000000"
 		)
 	fi
+	if [ "$scenario" = "pr-executable-group-writable" ]; then
+		chmod 0775 "$fake_strix"
+	fi
 	if [ "$scenario" = "report-known-internal-warning-sanitized" ]; then
 		env_cmd+=(
 			FAKE_STRIX_OUTSIDE_REPORT_DIR="$repo_root_dir/outside-strix-report"
@@ -5638,6 +5642,16 @@ run_filtered_gate_case_if_requested() {
 			"" \
 			""
 		;;
+	pr-executable-group-writable)
+		run_gate_case "pr-executable-group-writable" \
+			"vertex_ai/ready-primary" \
+			"" \
+			"1" \
+			"must not be group/world writable" \
+			"0" \
+			"" \
+			""
+		;;
 	vertex-primary-hallucinated-endpoint-fallback-success)
 		run_gate_case "vertex-primary-hallucinated-endpoint-fallback-success" \
 			"vertex_ai/hallucination-primary" \
@@ -8752,6 +8766,15 @@ run_gate_case "pr-executable-integrity-mismatch" \
 	"" \
 	""
 
+run_gate_case "pr-executable-group-writable" \
+	"vertex_ai/ready-primary" \
+	"" \
+	"1" \
+	"must not be group/world writable" \
+	"0" \
+	"" \
+	""
+
 run_gate_case "runtime-env-forwarding" \
 	"gemini/gemini-pro-3.1-preview" \
 	"" \