diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index 7524822632bae7..7e6adf2580ea7e 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -4026,6 +4026,9 @@ def test_flag_comparisons(self):
         self.assertNotEqual(d, c.flags)
         self.assertNotEqual(c.flags, d)
 
+        self.assertNotEqual(None, c.flags)
+        self.assertNotEqual(c.flags, None)
+
     @requires_IEEE_754
     def test_float_operation(self):
         Decimal = self.decimal.Decimal
diff --git a/Misc/NEWS.d/next/Library/2026-09-24-10-17-06.gh-issue-158063.Bx9Jpl.rst b/Misc/NEWS.d/next/Library/2026-09-24-10-17-06.gh-issue-158063.Bx9Jpl.rst
new file mode 100644
index 00000000000000..dcf1a167c8d1d4
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-09-24-10-17-06.gh-issue-158063.Bx9Jpl.rst
@@ -0,0 +1,3 @@
+Fix an out-of-bounds read in the C implementation of :mod:`decimal` when
+comparing the ``flags`` or ``traps`` of a :class:`~decimal.Context` with an
+object that is not a signal dict, such as ``None``.
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index ada9b02d690717..26666ddf5c75d6 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -795,7 +795,8 @@ signaldict_richcompare(PyObject *v, PyObject *w, int op)
     decimal_state *state = get_module_state_by_def(Py_TYPE(v));
     assert(PyDecSignalDict_Check(state, v));
 
-    if ((SdFlagAddr(v) == NULL) || (SdFlagAddr(w) == NULL)) {
+    if ((SdFlagAddr(v) == NULL) ||
+        (PyDecSignalDict_Check(state, w) && SdFlagAddr(w) == NULL)) {
         return value_error_ptr(INVALID_SIGNALDICT_ERROR_MSG);
     }