diff --git a/CHANGES b/CHANGES
index 5f645efa843..3724c65cab3 100644
--- a/CHANGES
+++ b/CHANGES
@@ -37,6 +37,9 @@ Features added
 Bugs fixed
 ----------
 
+* #8084: autodoc: KeyError is raised on documenting an attribute of the broken
+  class
+
 Testing
 --------
 
diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index 0a64b56e2b9..47f6bcb2506 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -1610,6 +1610,9 @@ def add_directive_header(self, sig: str) -> None:
                 annotations = get_type_hints(self.parent)
             except TypeError:
                 annotations = {}
+            except KeyError:
+                # a broken class found (refs: https://github.com/sphinx-doc/sphinx/issues/8084)
+                annotations = {}
 
             if self.objpath[-1] in annotations:
                 objrepr = stringify_typehint(annotations.get(self.objpath[-1]))
@@ -1980,6 +1983,9 @@ def add_directive_header(self, sig: str) -> None:
                 annotations = get_type_hints(self.parent)
             except TypeError:
                 annotations = {}
+            except KeyError:
+                # a broken class found (refs: https://github.com/sphinx-doc/sphinx/issues/8084)
+                annotations = {}
 
             if self.objpath[-1] in annotations:
                 objrepr = stringify_typehint(annotations.get(self.objpath[-1]))