diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index eee4da9a43..8807395585 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -595,3 +595,6 @@ contributors:
 * Eero Vuojolahti: contributor
 
 * Kian-Meng, Ang: contributor
+
+* Julia Eskew (doctoryes): contributor
+  - Fixed issue 5646, handle when the 'ancestors' attribute is not present in an object
diff --git a/ChangeLog b/ChangeLog
index 2bf37a089a..c9d86d070c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -191,6 +191,15 @@ Release date: TBA
   (Ie. not necessarily at the end)
 
 
+What's New in Pylint 2.12.3?
+============================
+Release date:
+
+* Fixed handling of missing 'ancestors' object attribute.
+
+  Closes #5646
+
+
 What's New in Pylint 2.12.2?
 ============================
 Release date: 2021-11-25
diff --git a/doc/whatsnew/2.12.rst b/doc/whatsnew/2.12.rst
index c47f2e91a9..586fc50d31 100644
--- a/doc/whatsnew/2.12.rst
+++ b/doc/whatsnew/2.12.rst
@@ -255,3 +255,7 @@ Other Changes
   or ``not in`` checks
 
   Closes #5323
+
+* Fixed handling of missing 'ancestors' object attribute.
+
+  Closes #5646
diff --git a/pylint/checkers/refactoring/implicit_booleaness_checker.py b/pylint/checkers/refactoring/implicit_booleaness_checker.py
index 6167e3e88f..3a06375c99 100644
--- a/pylint/checkers/refactoring/implicit_booleaness_checker.py
+++ b/pylint/checkers/refactoring/implicit_booleaness_checker.py
@@ -213,5 +213,5 @@ def base_classes_of_node(instance: nodes.ClassDef) -> List[str]:
         """Return all the classes names that a ClassDef inherit from including 'object'."""
         try:
             return [instance.name] + [x.name for x in instance.ancestors()]
-        except TypeError:
+        except (TypeError, AttributeError):
             return [instance.name]