diff --git a/app/system/impl/raspiblitz.py b/app/system/impl/raspiblitz.py
index 54f61f5..7e477bd 100644
--- a/app/system/impl/raspiblitz.py
+++ b/app/system/impl/raspiblitz.py
@@ -261,11 +261,11 @@ class RaspiBlitzSystem(SystemBase):
 
     async def change_password(self, type: str, old_password: str, new_password: str):
         # check just allowed type values
-        type = type.lower()
-        if type not in ["a", "b", "c"]:
+        if not type or type.lower() not in ["a", "b", "c"]:
             raise HTTPException(
                 status.HTTP_400_BAD_REQUEST, detail=f"unknown password type: {type}"
             )
+        type = type.lower()
 
         # check password formatting
         if not password_valid(old_password):
@@ -279,7 +279,8 @@ class RaspiBlitzSystem(SystemBase):
 
         # first check if old password is correct
         result = await exec_bash_command(
-            f'/home/admin/config.scripts/blitz.passwords.sh check {type} "{old_password}"'  # noqa: E501
+            f'/home/admin/config.scripts/blitz.passwords.sh check {type} "{old_password}"',  # noqa: E501
+            sensitive=True,
         )
         data = {}
         match result:
@@ -300,7 +301,7 @@ class RaspiBlitzSystem(SystemBase):
         if type == "c":
             # will set password c of both lnd & core lightning if installed/activated
             script_call = f'/home/admin/config.scripts/blitz.passwords.sh set c "{old_password}" "{new_password}"'  # noqa: E501
-        result = await exec_bash_command(script_call)
+        result = await exec_bash_command(script_call, sensitive=True)
         data = {}
         match result:
             case Ok(in_data):
diff --git a/app/system/models.py b/app/system/models.py
index 2f4a9b1..dc812fc 100644
--- a/app/system/models.py
+++ b/app/system/models.py
@@ -16,6 +16,13 @@ class LoginInput(BaseModel):
     ] = None
 
 
+class ChangePasswordInput(BaseModel):
+    old_password: constr(min_length=1)
+    new_password: constr(min_length=1)
+    # RaspiBlitz only: which password (a, b or c) to change
+    type: Optional[str] = None
+
+
 class APIPlatform(str, Enum):
     RASPIBLITZ = "raspiblitz"
     NATIVE_PYTHON = "native_python"
diff --git a/app/system/router.py b/app/system/router.py
index 6c0943c..fd75c75 100644
--- a/app/system/router.py
+++ b/app/system/router.py
@@ -1,5 +1,3 @@
-from typing import Optional
-
 from fastapi import APIRouter, HTTPException, Request, Response, status
 from fastapi.params import Depends, Query
 
@@ -14,6 +12,7 @@ from app.system.docs import (
     get_hw_info_json,
 )
 from app.system.models import (
+    ChangePasswordInput,
     ConnectionInfo,
     LoginInput,
     RawDebugLogData,
@@ -74,18 +73,10 @@ def refresh_token():
     response_description="if 200 OK - password change worked",
     dependencies=[Depends(JWTBearer())],
 )
-async def change_password_impl(
-    old_password: str,
-    new_password: str,
-    type: Optional[str] = Query(
-        None,
-        description=(
-            "ℹ️ Used in **RaspiBlitz only**. Password A, B or C. "
-            'Must be one of `["a", "b", "c"]`'
-        ),
-    ),
-):
-    return await change_password(type, old_password, new_password)
+async def change_password_impl(data: ChangePasswordInput):
+    return await change_password(
+        data.type, data.old_password, data.new_password
+    )
 
 
 @router.get(
diff --git a/tests/test_change_password.py b/tests/test_change_password.py
new file mode 100644
index 0000000..00b57a6
--- /dev/null
+++ b/tests/test_change_password.py
@@ -0,0 +1,50 @@
+"""
+Regression tests for the change-password endpoint.
+
+- Passwords were accepted as query parameters, so they leaked into access
+  logs, proxy logs and browser history. They must travel in the request body.
+- The RaspiBlitz password scripts were called without sensitive=True, so the
+  plaintext passwords were written to the debug log.
+"""
+
+from app.api.models import ProcessResult
+from app.external.result_type.src.result.result import Ok
+
+
+def test_change_password_uses_request_body_not_query():
+    from app.main import app
+
+    spec = app.openapi()
+    path = next(p for p in spec["paths"] if p.endswith("change-password"))
+    operation = spec["paths"][path]["post"]
+
+    param_names = {p["name"] for p in operation.get("parameters", [])}
+    assert "old_password" not in param_names, "password must not be a query param"
+    assert "new_password" not in param_names, "password must not be a query param"
+    assert "requestBody" in operation, "passwords must be sent in the request body"
+
+
+async def test_raspiblitz_change_password_calls_are_sensitive(monkeypatch):
+    from app.system.impl import raspiblitz as rb
+
+    # the shell-script existence check would exit(1) in the test env
+    monkeypatch.setattr(
+        rb.RaspiBlitzSystem, "_check_shell_scripts_status", lambda self: None
+    )
+    system = rb.RaspiBlitzSystem()
+    calls = []
+
+    async def fake_exec(command, **kwargs):
+        calls.append(kwargs)
+        # 'check' -> correct=1; 'set' -> no error key
+        return Ok(ProcessResult(0, "correct=1\n", ""))
+
+    monkeypatch.setattr(rb, "exec_bash_command", fake_exec)
+    monkeypatch.setattr(rb, "password_valid", lambda p: True)
+
+    await system.change_password("a", "oldpass12", "newpass12")
+
+    assert len(calls) == 2, "expected a check call and a set call"
+    assert all(c.get("sensitive") is True for c in calls), (
+        "password script calls must be marked sensitive so they aren't logged"
+    )