This was caught on oss-fuzz's ASAN builder:

Step #4: ==7656==ERROR: AddressSanitizer: heap-use-after-free on address 0x604001568ea0 at pc 0x7f603e4b974b bp 0x7ffe4f7e8f90 sp 0x7ffe4f7e8f88
Step #4: READ of size 8 at 0x604001568ea0 thread T0
Step #4:     #0 0x7f603e4b974a in module_free /src/cpython3/Modules/_zoneinfo.c:2610:10
Step #4:     #1 0x570311 in module_dealloc /src/cpython3/Objects/moduleobject.c:675:9
Step #4:     #2 0x57b7fc in _Py_Dealloc /src/cpython3/Objects/object.c:2209:5
Step #4:     #3 0x54ce60 in _Py_DECREF /src/cpython3/./Include/object.h:430:9
Step #4:     #4 0x551cdc in _Py_XDECREF /src/cpython3/./Include/object.h:497:9
Step #4:     #5 0x54e1b2 in insertdict /src/cpython3/Objects/dictobject.c:1129:5
Step #4:     #6 0x54d2fe in PyDict_SetItem /src/cpython3/Objects/dictobject.c:1579:12
Step #4:     #7 0x55b5dc in dict_ass_sub /src/cpython3/Objects/dictobject.c:2179:16
Step #4:     #8 0x87520f in PyObject_SetItem /src/cpython3/Objects/abstract.c:210:16
Step #4:     #9 0x6c1e89 in _PyImport_Cleanup /src/cpython3/Python/import.c:523:13
Step #4:     #10 0x6fc40a in Py_FinalizeEx /src/cpython3/Python/pylifecycle.c:1422:5
Step #4:     #11 0x4dd17a in Py_RunMain /src/cpython3/Modules/main.c:634:9
Step #4:     #12 0x4ddbea in pymain_main /src/cpython3/Modules/main.c:662:12
Step #4:     #13 0x4dde34 in Py_BytesMain /src/cpython3/Modules/main.c:686:12
Step #4:     #14 0x4dd030 in main /src/cpython3/./Programs/python.c:15:12
Step #4:     #15 0x7f60440bc82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
Step #4:     #16 0x434ce8 in _start (/src/cpython3/python+0x434ce8)
Step #4: 
Step #4: 0x604001568ea0 is located 16 bytes inside of 48-byte region [0x604001568e90,0x604001568ec0)
Step #4: freed by thread T0 here:
Step #4:     #0 0x4ad20d in free /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:123:3
Step #4:     #1 0x57c493 in _PyMem_RawFree /src/cpython3/Objects/obmalloc.c:127:5
Step #4:     #2 0x57dbc2 in PyObject_Free /src/cpython3/Objects/obmalloc.c:709:5
Step #4:     #3 0x75e81a in PyObject_GC_Del /src/cpython3/Modules/gcmodule.c:2325:5
Step #4:     #4 0x5a12cd in object_dealloc /src/cpython3/Objects/typeobject.c:4008:5
Step #4:     #5 0x59abbb in subtype_dealloc /src/cpython3/Objects/typeobject.c:1371:5
Step #4:     #6 0x57b7fc in _Py_Dealloc /src/cpython3/Objects/object.c:2209:5
Step #4:     #7 0x7f603e4b0700 in _Py_DECREF /src/cpython3/./Include/object.h:430:9
Step #4:     #8 0x7f603e4b05dc in _Py_XDECREF /src/cpython3/./Include/object.h:497:9
Step #4:     #9 0x7f603e4b96de in module_free /src/cpython3/Modules/_zoneinfo.c:2609:5
Step #4:     #10 0x570311 in module_dealloc /src/cpython3/Objects/moduleobject.c:675:9
Step #4:     #11 0x57b7fc in _Py_Dealloc /src/cpython3/Objects/object.c:2209:5
Step #4:     #12 0x54ce60 in _Py_DECREF /src/cpython3/./Include/object.h:430:9
Step #4:     #13 0x551cdc in _Py_XDECREF /src/cpython3/./Include/object.h:497:9
Step #4:     #14 0x54e1b2 in insertdict /src/cpython3/Objects/dictobject.c:1129:5
Step #4:     #15 0x54d2fe in PyDict_SetItem /src/cpython3/Objects/dictobject.c:1579:12
Step #4:     #16 0x55b5dc in dict_ass_sub /src/cpython3/Objects/dictobject.c:2179:16
Step #4:     #17 0x87520f in PyObject_SetItem /src/cpython3/Objects/abstract.c:210:16
Step #4:     #18 0x6c1e89 in _PyImport_Cleanup /src/cpython3/Python/import.c:523:13
Step #4:     #19 0x6fc40a in Py_FinalizeEx /src/cpython3/Python/pylifecycle.c:1422:5
Step #4:     #20 0x4dd17a in Py_RunMain /src/cpython3/Modules/main.c:634:9
Step #4:     #21 0x4ddbea in pymain_main /src/cpython3/Modules/main.c:662:12
Step #4:     #22 0x4dde34 in Py_BytesMain /src/cpython3/Modules/main.c:686:12
Step #4:     #23 0x4dd030 in main /src/cpython3/./Programs/python.c:15:12
Step #4:     #24 0x7f60440bc82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
Step #4: 
Step #4: previously allocated by thread T0 here:
Step #4:     #0 0x4ad48d in malloc /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:145:3
Step #4:     #1 0x57c37c in _PyMem_RawMalloc /src/cpython3/Objects/obmalloc.c:99:12
Step #4:     #2 0x57da49 in PyObject_Malloc /src/cpython3/Objects/obmalloc.c:685:12
Step #4:     #3 0x75e17c in _PyObject_GC_Alloc /src/cpython3/Modules/gcmodule.c:2233:26
Step #4:     #4 0x75e0c5 in _PyObject_GC_Malloc /src/cpython3/Modules/gcmodule.c:2260:12
Step #4:     #5 0x598619 in PyType_GenericAlloc /src/cpython3/Objects/typeobject.c:1086:15
Step #4:     #6 0x5a1922 in object_new /src/cpython3/Objects/typeobject.c:4002:12
Step #4:     #7 0x59d2c7 in type_call /src/cpython3/Objects/typeobject.c:1017:11
Step #4:     #8 0x4fbb0b in _PyObject_MakeTpCall /src/cpython3/Objects/call.c:191:18
Step #4:     #9 0x4feefa in _PyObject_VectorcallTstate /src/cpython3/./Include/cpython/abstract.h:116:16
Step #4:     #10 0x4fb5e7 in _PyObject_CallNoArgTstate /src/cpython3/./Include/internal/pycore_call.h:33:12
Step #4:     #11 0x4fdaa6 in _PyObject_CallFunctionVa /src/cpython3/Objects/call.c:515:16
Step #4:     #12 0x4fe32a in callmethod /src/cpython3/Objects/call.c:614:12
Step #4:     #13 0x4fe193 in PyObject_CallMethod /src/cpython3/Objects/call.c:634:24
Step #4:     #14 0x7f603e4b91b1 in new_weak_cache /src/cpython3/Modules/_zoneinfo.c:2483:9
Step #4:     #15 0x7f603e4b95ec in initialize_caches /src/cpython3/Modules/_zoneinfo.c:2503:31
Step #4:     #16 0x7f603e4b0905 in zoneinfomodule_exec /src/cpython3/Modules/_zoneinfo.c:2669:9
Step #4:     #17 0x56ea8a in PyModule_ExecDef /src/cpython3/Objects/moduleobject.c:399:23
Step #4:     #18 0x6c8e0d in exec_builtin_or_dynamic /src/cpython3/Python/import.c:2242:12
Step #4:     #19 0x6c8d30 in _imp_exec_dynamic_impl /src/cpython3/Python/import.c:2316:12
Step #4:     #20 0x6c7c15 in _imp_exec_dynamic /src/cpython3/Python/clinic/import.c.h:358:21
Step #4:     #21 0x8cca28 in cfunction_vectorcall_O /src/cpython3/Objects/methodobject.c:510:24
Step #4:     #22 0x4fc8b4 in PyVectorcall_Call /src/cpython3/Objects/call.c:230:16
Step #4:     #23 0x4fc9b3 in _PyObject_Call /src/cpython3/Objects/call.c:265:16
Step #4:     #24 0x4fcb20 in PyObject_Call /src/cpython3/Objects/call.c:292:12
Step #4:     #25 0x679ff0 in do_call_core /src/cpython3/Python/ceval.c
Step #4:     #26 0x66942a in _PyEval_EvalFrameDefault /src/cpython3/Python/ceval.c:3607:22
Step #4:     #27 0x661fce in _PyEval_EvalFrame /src/cpython3/./Include/internal/pycore_ceval.h:40:12
Step #4:     #28 0x67b5a7 in _PyEval_EvalCode /src/cpython3/Python/ceval.c:4354:14
Step #4:     #29 0x4fce97 in _PyFunction_Vectorcall /src/cpython3/Objects/call.c:395:12

https://oss-fuzz-build-logs.storage.googleapis.com/log-42158c8c-476d-482a-ab04-75ea905e483c.txt

Sending out a patch shortly.