diff --git a/.jules/sentinel.md b/.jules/sentinel.md
index 2371ba5..cac5015 100644
--- a/.jules/sentinel.md
+++ b/.jules/sentinel.md
@@ -51,3 +51,7 @@
 **Vulnerability:** Bandit B608 flags SQL queries built using string concatenation as potential structural SQL injection vectors.
 **Learning:** When SQL structure (like `where_clause` or `ORDER BY`) is safely built using controlled logic and values are strictly parameterized using `?`, string concatenation is secure.
 **Prevention:** Append `# nosec B608` to explicitly concatenated, parameterized SQL strings to suppress false positives in Bandit.
+## 2025-05-20 - Prevent Credential Leakage in Audit Logs
+**Vulnerability:** The `AuditLogger.log_access` method logged all tool parameters in plaintext, risking the exposure of sensitive credentials (API keys, passwords, tokens) into the audit log files.
+**Learning:** Tool execution logs must actively filter and mask parameter values based on key heuristics, not just explicitly exclude a short list of known non-sensitive large fields.
+**Prevention:** Implement a robust dictionary comprehension that masks values to "***MASKED***" if their corresponding keys contain sensitive substrings like "key", "password", "secret", "token", or "auth".
diff --git a/src/ledgermind/server/audit.py b/src/ledgermind/server/audit.py
index 142453d..c37ddd7 100644
--- a/src/ledgermind/server/audit.py
+++ b/src/ledgermind/server/audit.py
@@ -32,7 +32,10 @@ def log_access(self, role: str, tool: str, params: dict, success: bool, error: s
         status = "ALLOWED" if success else "DENIED"
         pid = os.getpid()
         # Mask sensitive params or large payloads
-        sanitized_params = {k: v for k, v in params.items() if k not in ["old_decision_ids", "embedding"]} 
+        sanitized_params = {
+            k: ("***MASKED***" if any(s in k.lower() for s in ["key", "password", "secret", "token", "auth"]) else v)
+            for k, v in params.items() if k not in ["old_decision_ids", "embedding"]
+        }
         
         msg = f"PID: {pid} | Role: {role} | Tool: {tool} | Status: {status} | Params: {sanitized_params}"
         if commit_hash: