diff --git a/.env.demo b/.env.demo
index 3079e8ac..f8a9a888 100644
--- a/.env.demo
+++ b/.env.demo
@@ -96,8 +96,6 @@ MAX_UPLOAD_SIZE=1073741824
 # Allowed request headers (use * to allow all)
 # CORS_ALLOWED_HEADERS=*
 
-# **Rate Limiting** (see SECURITY_AUDIT.md and docs/API.md)
-
 # **Audit Logging & SIEM Integration** (see docs/ConfigurationGuide.md#audit-logging)
 # Enable HTTP request audit logging middleware
 AUDIT_LOGGING_ENABLED=true
diff --git a/app/utils/audit_service.py b/app/utils/audit_service.py
index c2b0ecd5..73a6af7c 100644
--- a/app/utils/audit_service.py
+++ b/app/utils/audit_service.py
@@ -12,6 +12,7 @@ Supported SIEM transports:
 
 import json
 import logging
+import re
 import socket
 import threading
 from datetime import datetime, timezone
@@ -297,13 +298,24 @@ def _send_http(payload: dict[str, Any]) -> None:
         headers["Authorization"] = f"Bearer {token}"
 
     # Parse custom headers (comma-separated "Key:Value" pairs).
+    # Reject headers that could override security-critical ones already set,
+    # and validate that header names contain only RFC 7230 token characters.
+    _PROTECTED_HEADERS = {"authorization", "content-type", "host"}
+    _VALID_HEADER_NAME = re.compile(r"^[A-Za-z0-9!#$%&'*+\-.^_`|~]+$")
     raw_custom = settings.audit_siem_http_custom_headers
     if raw_custom:
         for raw_pair in raw_custom.split(","):
             pair = raw_pair.strip()
             if ":" in pair:
                 k, _, v = pair.partition(":")
-                headers[k.strip()] = v.strip()
+                name = k.strip()
+                if not name or not _VALID_HEADER_NAME.match(name):
+                    logger.warning("Skipping invalid SIEM custom header name: %r", name)
+                    continue
+                if name.lower() in _PROTECTED_HEADERS:
+                    logger.warning("Skipping protected SIEM custom header: %r", name)
+                    continue
+                headers[name] = v.strip()
 
     # Wrap in Splunk HEC-style envelope when URL contains ``/services/collector``.
     body: dict[str, Any]
diff --git a/frontend/templates/audit_logs.html b/frontend/templates/audit_logs.html
index 7a015511..92073816 100644
--- a/frontend/templates/audit_logs.html
+++ b/frontend/templates/audit_logs.html
@@ -72,7 +72,7 @@
         <label for="filter-resource" class="block text-xs font-medium text-gray-500 dark:text-gray-400 mb-1">Resource Type</label>
         <input id="filter-resource" type="text" x-model.debounce.300ms="filters.resource_type" @input="fetchLogs()"
                placeholder="e.g. document, user"
-               class="w-full rounded-md border-gray-300 dark:border-gray-600 dark:bg-gray-700 dark:text-white text-sm">
+               class="w-full rounded-md border-gray-300 dark:border-gray-600 dark:bg-gray-700 dark:text-white text-sm min-h-[44px]">
       </div>
     </div>
   </section>