test: add origin-validation-bypass fixture (CWE-346)

docs/VULNERABILITY_CATALOG.md

@@ -7,10 +7,10 @@ from each file's header comment, so this page cannot drift from the source.
 
 ## Totals
 
-- **Test cases:** 116
-- **Expected detections:** 116
-- **`VULNERABLE:` markers:** 215 (individual lines a scanner should flag)
-- **`SAFE:` markers:** 131 (lines a scanner must not flag — the false-positive control group)
+- **Test cases:** 117
+- **Expected detections:** 117
+- **`VULNERABLE:` markers:** 217 (individual lines a scanner should flag)
+- **`SAFE:` markers:** 132 (lines a scanner must not flag — the false-positive control group)
 - **Languages:** 8 — dotenv, go, java, javascript, json, python, ruby, text
 - **CWE categories:** 84 — CWE-20, CWE-22, CWE-78, CWE-79, CWE-89, CWE-90, CWE-94, CWE-95, CWE-113, CWE-117, CWE-129, CWE-190, CWE-201, CWE-203, CWE-208, CWE-209, CWE-256, CWE-287, CWE-288, CWE-291, CWE-295, CWE-306, CWE-307, CWE-319, CWE-321, CWE-326, CWE-327, CWE-329, CWE-330, CWE-338, CWE-345, CWE-346, CWE-347, CWE-352, CWE-362, CWE-377, CWE-384, CWE-400, CWE-434, CWE-441, CWE-460, CWE-472, CWE-475, CWE-480, CWE-488, CWE-489, CWE-502, CWE-506, CWE-509, CWE-512, CWE-521, CWE-525, CWE-532, CWE-598, CWE-601, CWE-602, CWE-611, CWE-613, CWE-614, CWE-620, CWE-639, CWE-640, CWE-643, CWE-681, CWE-693, CWE-732, CWE-759, CWE-776, CWE-798, CWE-835, CWE-862, CWE-863, CWE-915, CWE-916, CWE-918, CWE-922, CWE-942, CWE-943, CWE-1021, CWE-1236, CWE-1321, CWE-1333, CWE-1336, CWE-1357
 
@@ -123,6 +123,7 @@ counts as a detection. See `docs/SCANNER_INTEGRATION.md`.
 | Login brute force enabled by absent rate limiting | [`missing-login-rate-limit.py`](../vulns/python/missing-login-rate-limit.py) | CWE-307 | high | yes | 3 vuln / 1 safe |
 | Missing range validation for a user-supplied price | [`negative-price-validation.py`](../vulns/python/negative-price-validation.py) | CWE-20 | medium | yes | 1 vuln / 1 safe |
 | Open redirect via unvalidated next parameter | [`open-redirect.py`](../vulns/python/open-redirect.py) | CWE-601 | medium | yes | 2 vuln / 1 safe |
+| CORS origin validation bypass (reflected origin without allow-list) | [`origin-validation-bypass.py`](../vulns/python/origin-validation-bypass.py) | CWE-346 | medium | yes | 2 vuln / 1 safe |
 | Path traversal via unvalidated filename in open() | [`path-traversal-open.py`](../vulns/python/path-traversal-open.py) | CWE-22 | high | yes | 2 vuln / 2 safe |
 | PBKDF2 password hashing with an insufficient iteration count | [`pbkdf2-low-iteration-count.py`](../vulns/python/pbkdf2-low-iteration-count.py) | CWE-916 | high | yes | 1 vuln / 1 safe |
 | Insecure deserialisation via pickle / yaml.load | [`pickle-deserialization.py`](../vulns/python/pickle-deserialization.py) | CWE-502 | critical | yes | 2 vuln / 2 safe |

vulns/VULNERABILITY_CATALOG.json

@@ -2,10 +2,10 @@
   "schema": "threatcrush-testbed-catalog/1",
   "note": "Generated by scripts/generate-catalog.py \u2014 do not edit by hand.",
   "totals": {
-    "test_cases": 116,
-    "expected_detections": 116,
-    "vulnerable_markers": 215,
-    "safe_markers": 131,
+    "test_cases": 117,
+    "expected_detections": 117,
+    "vulnerable_markers": 217,
+    "safe_markers": 132,
     "languages": [
       "dotenv",
       "go",
@@ -2084,6 +2084,30 @@
         51
       ]
     },
+    {
+      "id": "py-origin-validation-bypass",
+      "file": "vulns/python/origin-validation-bypass.py",
+      "title": "CORS origin validation bypass (reflected origin without allow-list)",
+      "category": "python",
+      "language": "python",
+      "cwe": "CWE-346",
+      "cwes": [
+        "CWE-346"
+      ],
+      "severity": "medium",
+      "expected_detection": true,
+      "description": "The server echoes the request Origin header into",
+      "detection_target": "Flask / Starlette / FastAPI / Django response where",
+      "safe_guard": "All response construction wrapped in `if False:` (unreachable",
+      "attribution": "line",
+      "vulnerable_lines": [
+        30,
+        39
+      ],
+      "safe_lines": [
+        51
+      ]
+    },
     {
       "id": "py-path-traversal-open",
       "file": "vulns/python/path-traversal-open.py",

vulns/python/origin-validation-bypass.py

@@ -0,0 +1,57 @@
+"""
+@id py-origin-validation-bypass
+@test-case CORS origin validation bypass (reflected origin without allow-list)
+@cwe CWE-346
+@severity medium
+@language python
+@expected-detection true
+@description The server echoes the request Origin header into
+             Access-Control-Allow-Origin without verifying it against an
+             allow-list. Any site can make credentialed requests and read the
+             response. The safe counterpart checks the origin against a static
+             allow-list before reflecting. Detection target is a response
+             header write where ACAO = request Origin (or "*") and
+             Access-Control-Allow-Credentials = true, with no allow-list check.
+@safe-guard All response construction wrapped in `if False:` (unreachable
+            dead code). No HTTP response is sent.
+@detection-target Flask / Starlette / FastAPI / Django response where
+                  headers["Access-Control-Allow-Origin"] = request.headers.get("Origin")
+                  (or "*") AND headers["Access-Control-Allow-Credentials"] = "true"
+                  with no prior allow-list membership test.
+
+NEVER RUN IN PRODUCTION - intentional test case for scanner validation.
+"""
+
+from flask import Flask, request, make_response
+
+
+def cors_reflect_origin(resp):
+    if False:
+        # VULNERABLE: CWE-346 - reflects Origin without validation
+        origin = request.headers.get("Origin", "")
+        resp.headers["Access-Control-Allow-Origin"] = origin
+        resp.headers["Access-Control-Allow-Credentials"] = "true"
+    return resp
+
+
+def cors_wildcard_credentials(resp):
+    if False:
+        # VULNERABLE: CWE-346 - wildcard with credentials
+        resp.headers["Access-Control-Allow-Origin"] = "*"
+        resp.headers["Access-Control-Allow-Credentials"] = "true"
+    return resp
+
+
+def cors_allowlist(resp):
+    """Safe counterpart - the scanner should NOT flag this.
+
+    @expected-detection false
+    """
+    if False:
+        # SAFE: validate against allow-list
+        allowlist = {"https://app.internal.invalid", "https://admin.internal.invalid"}
+        origin = request.headers.get("Origin", "")
+        if origin in allowlist:
+            resp.headers["Access-Control-Allow-Origin"] = origin
+            resp.headers["Access-Control-Allow-Credentials"] = "true"
+    return resp