fix: harden server input validation and prevent information leakage.

web/server/bridge/retrieve.py

@@ -42,11 +42,11 @@ def main():
         try:
             req = json.loads(raw_line)
             query = req.get("query", "")
-            top_n = int(req.get("top_n", 5))
+            top_n = max(1, min(int(req.get("top_n", 5)), 20))
             results, latency = retriever.retrieve(query, top_n=top_n)
             response = {"results": results, "latency_seconds": round(latency, 4)}
-        except Exception as exc:
-            response = {"error": str(exc)}
+        except Exception:
+            response = {"error": "retrieval_failed"}
 
         sys.stdout.write(json.dumps(response) + "\n")
         sys.stdout.flush()

web/server/index.js

@@ -99,8 +99,8 @@ for (const c of chunks) {
   chunksByStd[c.standard_id].push(c);
 }
 
-/** @type {RegExp} - Matches ASCII control characters that should be stripped from user input. */
-const CONTROL_CHAR_RE = /[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/g;
+/** @type {RegExp} - Matches ASCII control characters and Unicode BiDi override characters that should be stripped from user input. */
+const CONTROL_CHAR_RE = /[\x00-\x08\x0B\x0C\x0E-\x1F\x7F\u202A-\u202E\u2066-\u2069]/g;
 
 /**
  * Strips control characters and truncates a string to a safe length.
@@ -114,8 +114,8 @@ function sanitizeText(value, maxLen = 500) {
   return value.replace(CONTROL_CHAR_RE, "").slice(0, maxLen).trim();
 }
 
-/** @type {RegExp} - Accepts IS standard IDs: letters, digits, spaces, colons, parens, dots, hyphens, slashes. */
-const STANDARD_ID_RE = /^[A-Za-z0-9 :()./-]{1,60}$/;
+/** @type {RegExp} - Accepts IS standard IDs: letters, digits, spaces, colons, parens, dots, hyphens. */
+const STANDARD_ID_RE = /^[A-Za-z0-9 :().-]{1,60}$/;
 
 /**
  * Returns true if the value is a well-formed IS standard identifier.
@@ -336,7 +336,7 @@ app.post("/api/recommend", async (req, res) => {
   const totalMs = Date.now() - t0;
 
   log("POST /api/recommend", {
-    query: effectiveQuery,
+    query: sanitizeText(effectiveQuery, 200),
     results: retrieved.length,
     retrieval_ms: retrievalMs,
     llm_ms: llmMs,

web/server/services/retrieverService.js

@@ -21,8 +21,14 @@ const { EventEmitter } = require("events");
 const BRIDGE  = path.join(__dirname, "../bridge/retrieve.py");
 /** @type {string} - Repository root, used as cwd for the Python subprocess. */
 const ROOT    = path.join(__dirname, "../../..");
-/** @type {string} - Python executable; override with PYTHON_BIN env var. */
-const PYTHON  = process.env.PYTHON_BIN || "python";
+/** @type {string} - Python executable; override with PYTHON_BIN env var (must be "python", "python3", or an absolute path to a Python interpreter). */
+const _pythonRaw = process.env.PYTHON_BIN || "python";
+const _PYTHON_ALLOWLIST = /^(python[23]?|\/[^\0]+)$/;
+if (!_PYTHON_ALLOWLIST.test(_pythonRaw)) {
+  console.error(`[retriever] Invalid PYTHON_BIN value: ${JSON.stringify(_pythonRaw)}. Must be "python", "python3", or an absolute path.`);
+  process.exit(1);
+}
+const PYTHON = _pythonRaw;
 
 /** @type {number} - Maximum milliseconds to wait for the daemon to signal ready on cold start. */
 const BOOT_TIMEOUT_MS  = 90_000;
@@ -131,9 +137,17 @@ class PythonRetriever extends EventEmitter {
     if (msg.error) {
       item.reject(new Error(msg.error));
     } else {
+      const raw = Array.isArray(msg.results) ? msg.results : [];
+      const ALLOWED = new Set(["standard_id", "title", "category", "matched_section", "score"]);
+      const results = raw.map((r) => {
+        if (typeof r !== "object" || r === null) return null;
+        const safe = {};
+        for (const k of ALLOWED) if (k in r) safe[k] = r[k];
+        return safe;
+      }).filter(Boolean);
       item.resolve({
-        results:          msg.results        || [],
-        latency_seconds:  msg.latency_seconds ?? 0,
+        results,
+        latency_seconds: typeof msg.latency_seconds === "number" ? msg.latency_seconds : 0,
       });
     }
   }

web/server/start.js

@@ -3,8 +3,14 @@
  * Kills any process already on PORT before starting index.js.
  * Run with: node web/server/start.js
  */
-const { execSync, spawn } = require("child_process");
-const PORT = process.env.PORT || 5000;
+const { execSync, spawnSync, spawn } = require("child_process");
+
+const rawPort = process.env.PORT || "5000";
+const PORT = parseInt(rawPort, 10);
+if (!Number.isInteger(PORT) || PORT < 1 || PORT > 65535) {
+  console.error(`[start] Invalid PORT value: ${JSON.stringify(rawPort)}`);
+  process.exit(1);
+}
 
 function killPort(port) {
   try {
@@ -18,10 +24,10 @@ function killPort(port) {
       }
       for (const pid of pids) {
         console.log(`[start] Killing stale process PID ${pid} on port ${port}`);
-        execSync(`taskkill /PID ${pid} /F`, { stdio: "ignore" });
+        spawnSync("taskkill", ["/PID", pid, "/F"], { stdio: "ignore" });
       }
     } else {
-      execSync(`fuser -k ${port}/tcp`, { stdio: "ignore" });
+      spawnSync("fuser", [`${port}/tcp`, "-k"], { stdio: "ignore" });
     }
   } catch {
     // No process on that port -- fine