BUG #15737: Unexpectedly Deleting full table when referring CTE (With Clause ) data,in a Subquery in another CTE

The following bug has been logged on the website:

Bug reference: 15737
Logged by: Chandan Ahuja
Email address: chandanahuja7(at)gmail(dot)com
PostgreSQL version: 11.1
Operating system: RHEL
Description:

Hi ,

I faced this unexpected behavior when i use CTE (WITH clause) query to
delete the rows from multiple tables. Because of which my entire data-set
has been deleted. It looks like this is a bug.

I have 3 tables , (1)Contract , (2)ContractComponent and (3)ContractRole.
Lets call them CT, CC and CR respectively.
CT has One-To-Many relation with CC
CC has One-To-Many relation with CR.
Table Structure:
(1)Contract (contract_id(PK) ) , (2)ContractComponent
(Contractcomponent_id(PK) , contract_id(FK) ), (3)ContractRole
(ContractRole_id(PK) , ContractComponent_id (FK),
party_source_system_record_pk ).

I have applied Foreign Key constraint in these 3 tables with On-Delete
Cascade option.

I wanted to delete ONLY one particular Contract (CT) record and its
corresponding records in CC and CR tables so I made the following query.
This Query is giving 2 strange results which i am not able to fathom, and it
appears to me that it is a BUG.

ISSUES/BUG:

1. Contract_id column is not specified in the Select clause of "deletedata "
, still PostgreSQL does not complains in the "delct" and goes on to execute
the SQL.
2. But the bigger issue is that on execution it deletes all the records from
the Contract and ContractComponent table, and not just the one meeting the
filter clause specified (where cr.party_source_system_record_pk =
'20000151686').

------------------------------------------------------------------------------------------------------------------------------------------------------------

with deletedata as
(
select cc.contractcomponent_id
---- Contract_id column is not specified in the Select clause of
"deletedata" , still PostgreSQL does not complains in the "delct"
from
core.contractrole cr
join core.contractcomponent cc on cc.contractcomponent_id =
cr.contractcomponent_id
join core.contract ct on cc.contract_id = ct.contract_id
where
cr.party_source_system_record_pk = '20000151686'
)
, delcc as
(
delete from core.contractcomponent where contractcomponent_id in ( select
distinct contractcomponent_id from deletedata)
-- returning contractcomponent_id
)
, delct as
(
-- I am referring contract_id column here from deletedata but it does not
exist
delete from core.contract where contract_id in ( select distinct contract_id
from deletedata) -- returning contract_id
)
select distinct contractcomponent_id from deletedata
------------------------------------------------------------------------------------------------------------------------------------------------------------

Thanks an anticipation.