diff --git a/README.md b/README.md
index 1db48cc..7b5d439 100644
--- a/README.md
+++ b/README.md
@@ -103,6 +103,9 @@ docksec --image-only -i myapp:latest
 # Fast scan only (no AI)
 docksec Dockerfile --scan-only
 
+# Choose which severity levels the image scan reports (default: CRITICAL,HIGH)
+docksec -i myapp:latest --image-only --severity CRITICAL,HIGH,MEDIUM
+
 # Reduce output to warnings, errors, and the result summary
 docksec Dockerfile --scan-only --quiet
 
diff --git a/docksec/cli.py b/docksec/cli.py
index 2f4b489..230cd7a 100644
--- a/docksec/cli.py
+++ b/docksec/cli.py
@@ -52,6 +52,7 @@ def main() -> None:
     parser.add_argument('--model', help='Model name to use (e.g., gpt-4o, claude-haiku-4-5, gemini-1.5-pro, llama3.1)')
     parser.add_argument('--compact-output', action='store_true', help='Use compact output format (less verbose)')
     parser.add_argument('--skip-ai-scoring', action='store_true', help='Skip AI-based security scoring (use local scoring only)')
+    parser.add_argument('--severity', help='Comma-separated severity levels to scan for (default: CRITICAL,HIGH; or set DOCKSEC_DEFAULT_SEVERITY)')
     parser.add_argument('--quiet', action='store_true', help='Reduce output to warnings, errors, and the result summary')
     parser.add_argument('--no-color', action='store_true', help='Disable colored output (also honors the NO_COLOR env var)')
     parser.add_argument('--version', action='version', version=f'DockSec {get_version()}')
@@ -76,7 +77,21 @@ def main() -> None:
     # Set compact output mode if requested
     if args.compact_output:
         os.environ["DOCKSEC_COMPACT_OUTPUT"] = "true"
-    
+
+    # Resolve the severity filter: CLI flag > DOCKSEC_DEFAULT_SEVERITY env > default.
+    from docksec.config_manager import get_config
+    from docksec.enums import Severity
+    severity = args.severity or get_config().default_severity
+    severity_list = [s.strip().upper() for s in severity.split(',') if s.strip()]
+    invalid_severities = [s for s in severity_list if s not in Severity.values()]
+    if not severity_list or invalid_severities:
+        output.error(
+            f"Invalid --severity value '{severity}'. "
+            f"Valid levels: {', '.join(Severity.values())}"
+        )
+        sys.exit(1)
+    severity = ','.join(severity_list)
+
     # Validate argument combinations
     if args.image_only and args.ai_only:
         output.error("--image-only and --ai-only cannot be used together (AI analysis requires a Dockerfile)")
@@ -162,6 +177,8 @@ def main() -> None:
 
     output.banner(get_version(), mode_desc)
     output.kv("Reports", RESULTS_DIR)
+    if run_scan:
+        output.kv("Severity", severity)
     if run_ai:
         config = get_config()
         output.kv("AI Provider", str(config.llm_provider))
@@ -238,7 +255,7 @@ def main() -> None:
                     skip_ai_scoring=args.skip_ai_scoring
                 )
                 output.info(f"Scanning Compose file: {args.compose}")
-                results = orchestrator.run_full_scan("CRITICAL,HIGH")
+                results = orchestrator.run_full_scan(severity)
 
                 # We need a scanner instance just for scoring and reporting
                 scanner = DockerSecurityScanner(None, None, scan_only=not run_ai, skip_ai_scoring=args.skip_ai_scoring)
@@ -258,10 +275,10 @@ def main() -> None:
                 if args.image_only:
                     # Image-only scan - skip Dockerfile analysis
                     output.info(f"Scanning Docker image: {args.image}")
-                    results = scanner.run_image_only_scan("CRITICAL,HIGH")
+                    results = scanner.run_image_only_scan(severity)
                 else:
                     # Full scan including Dockerfile
-                    results = scanner.run_full_scan("CRITICAL,HIGH")
+                    results = scanner.run_full_scan(severity)
 
             # Calculate security score
             scanner.analysis_score = scanner.get_security_score(results)
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 8d4aed3..295fd28 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **Redesigned terminal output**: a consolidated result summary with a box-drawing severity table, the security score with a color-coded rating, a "Quick take" action block highlighting the most important findings, the list of generated reports, and a suggested next command.
 - `--quiet` flag to reduce output to warnings, errors, and the result summary.
 - `--no-color` flag (also honors the `NO_COLOR` environment variable) to disable colored output.
+- `--severity` flag to choose which severity levels the image vulnerability scan reports (default `CRITICAL,HIGH`; also settable via `DOCKSEC_DEFAULT_SEVERITY`). Invalid values are rejected with a clear error.
 
 ### Changed
 - **Cleaner terminal output**: internal logs now write to `stderr` instead of `stdout` and stay quiet in CLI mode, so raw location-tagged log lines no longer interleave with the tool's user-facing messages. Set `DOCKSEC_LOG_LEVEL` to restore verbose logging.
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 9bb811d..7922b37 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -163,6 +163,39 @@ def test_model_flag_sets_env(self, mock_scanner_class):
                 # This tests that the env var would be set
                 pass
 
+    @patch('sys.argv', ['docksec', '--image-only', '-i', 'test:latest', '--severity', 'BOGUS'])
+    def test_invalid_severity_is_rejected(self):
+        """An invalid --severity value should error out and exit non-zero."""
+        from docksec.cli import main
+
+        with patch('builtins.print'):
+            with self.assertRaises(SystemExit) as ctx:
+                main()
+        self.assertEqual(ctx.exception.code, 1)
+
+    @patch('sys.argv', ['docksec', '--image-only', '-i', 'test:latest', '--severity', 'critical'])
+    @patch('docksec.docker_scanner.DockerSecurityScanner')
+    def test_severity_flag_threads_to_scanner(self, mock_scanner_class):
+        """A valid --severity should be normalized and passed to the scan call."""
+        from docksec.cli import main
+
+        scanner = Mock()
+        mock_scanner_class.return_value = scanner
+        scanner.run_image_only_scan.return_value = {
+            'json_data': [],
+            'dockerfile_scan': {'skipped': True},
+            'image_scan': {'skipped': False},
+            'scan_mode': 'image_only',
+        }
+        scanner.get_security_score.return_value = 90.0
+        scanner.generate_all_reports.return_value = {'json': 'x'}
+        scanner.RESULTS_DIR = '/tmp'
+
+        main()
+
+        # 'critical' is normalized to 'CRITICAL' and passed to the image scan.
+        scanner.run_image_only_scan.assert_called_once_with('CRITICAL')
+
     @patch('sys.argv', ['docksec', '/no/such/docksec_dockerfile_xyz', '--quiet', '--no-color'])
     def test_quiet_and_no_color_flags_are_accepted(self):
         """--quiet and --no-color must parse (argparse exits 2 on unknown flags)."""