diff --git a/supervisor/utils/codenotary.py b/supervisor/utils/codenotary.py
index bc4f3b817..c08e20f7f 100644
--- a/supervisor/utils/codenotary.py
+++ b/supervisor/utils/codenotary.py
@@ -21,6 +21,7 @@ _CAS_CMD: str = (
 _CACHE: set[tuple[str, str]] = set()
 
 
+_ATTR_ERROR: Final = "error"
 _ATTR_STATUS: Final = "status"
 
 
@@ -88,6 +89,9 @@ async def cas_validate(
             f"Can't parse CodeNotary output: {data!s} - {err!s}", _LOGGER.error
         ) from err
 
+    if _ATTR_ERROR in data_json:
+        raise CodeNotaryBackendError(data_json[_ATTR_ERROR], _LOGGER.warning)
+
     if data_json[_ATTR_STATUS] == 0:
         _CACHE.add((checksum, signer))
     else:
diff --git a/tests/utils/test_codenotary.py b/tests/utils/test_codenotary.py
index 68c5ed3b6..68d8617da 100644
--- a/tests/utils/test_codenotary.py
+++ b/tests/utils/test_codenotary.py
@@ -1,11 +1,51 @@
 """Test CodeNotary."""
+from __future__ import annotations
+
+from dataclasses import dataclass
+from unittest.mock import AsyncMock, Mock, patch
 
 import pytest
 
-from supervisor.exceptions import CodeNotaryUntrusted
+from supervisor.exceptions import (
+    CodeNotaryBackendError,
+    CodeNotaryError,
+    CodeNotaryUntrusted,
+)
 from supervisor.utils.codenotary import calc_checksum, cas_validate
 
 
+@dataclass
+class SubprocessResponse:
+    """Class for specifying subprocess exec response."""
+
+    returncode: int = 0
+    data: str = ""
+    error: str | None = None
+    exception: Exception | None = None
+
+
+@pytest.fixture(name="subprocess_exec")
+def fixture_subprocess_exec(request):
+    """Mock subprocess exec with specific return."""
+    response = request.param
+    if response.exception:
+        communicate_return = AsyncMock(side_effect=response.exception)
+    else:
+        err_return = None
+        if response.error:
+            err_return = Mock(decode=Mock(return_value=response.error))
+
+        communicate_return = AsyncMock(return_value=(response.data, err_return))
+
+    exec_return = Mock(returncode=response.returncode, communicate=communicate_return)
+
+    with patch(
+        "supervisor.utils.codenotary.asyncio.create_subprocess_exec",
+        return_value=exec_return,
+    ) as subprocess_exec:
+        yield subprocess_exec
+
+
 def test_checksum_calc():
     """Calc Checkusm as test."""
     assert calc_checksum("test") == calc_checksum(b"test")
@@ -30,3 +70,46 @@ async def test_invalid_checksum():
             "notary@home-assistant.io",
             "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
         )
+
+
+@pytest.mark.parametrize(
+    "subprocess_exec",
+    [
+        SubprocessResponse(returncode=1, error="test"),
+        SubprocessResponse(returncode=0, data='{"error":"asn1: structure error"}'),
+    ],
+    indirect=True,
+)
+async def test_cas_backend_error(subprocess_exec):
+    """Test backend error executing cas command."""
+    with pytest.raises(CodeNotaryBackendError):
+        await cas_validate(
+            "notary@home-assistant.io",
+            "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
+        )
+
+
+@pytest.mark.parametrize(
+    "subprocess_exec",
+    [SubprocessResponse(returncode=0, data='{"status":1}')],
+    indirect=True,
+)
+async def test_cas_notarized_untrusted(subprocess_exec):
+    """Test cas found notarized but untrusted content."""
+    with pytest.raises(CodeNotaryUntrusted):
+        await cas_validate(
+            "notary@home-assistant.io",
+            "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
+        )
+
+
+@pytest.mark.parametrize(
+    "subprocess_exec", [SubprocessResponse(exception=OSError())], indirect=True
+)
+async def test_cas_exec_os_error(subprocess_exec):
+    """Test os error attempting to execute cas command."""
+    with pytest.raises(CodeNotaryError):
+        await cas_validate(
+            "notary@home-assistant.io",
+            "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
+        )