PostgreSQL 17 backend segfault on second role-membership GRANT with explicit grantor

[rjbowes32]

Summary

A documented PostgreSQL 17 role-membership operation terminated the backend with signal 11 on two consecutive official Supabase Postgres images. Both attempts used isolated temporary storage, no published port, no network, and synthetic roles.

Exact runtime identities

Image tag	Repository digest	PostgreSQL evidence	Platform evidence	Outcome
public.ecr.aws/supabase/postgres:17.6.1.140	public.ecr.aws/supabase/postgres@sha256:6501843661b1f8ff97e85c02de33edc0ee2e2693888ad596ee86222f02dc8ecc	major 17, preflight-verified; 17.6.1.140 is the image tag version	linux/arm64 is inferred from the same local host/runtime architecture; a per-run platform line was not retained	backend terminated by signal 11
public.ecr.aws/supabase/postgres:17.6.1.141	public.ecr.aws/supabase/postgres@sha256:ba10e934f0a59990379f78ab9ed93926f1c291dd61a12fe4026f4202f1b89770	major 17, preflight-verified; 17.6.1.141 is the image tag version	linux/arm64, directly captured before SQL	backend terminated by signal 11

The .140 platform value is deliberately labelled as an inference, not independent per-image evidence.

The retained evidence did not capture the exact output of SELECT version(). Accordingly, this report does not present 17.6.1 as an upstream server-version string; it reports verified PostgreSQL major 17 and keeps the complete Supabase image versions in their tags.

Synthetic role topology

The failing statement ran with this bounded topology:

1. The image bootstrap administrator established a login-capable, non-superuser, NOINHERIT, CREATEROLE executor.
2. The executor created a non-login, non-superuser, non-CREATEROLE, NOINHERIT owner.
3. PostgreSQL 17 had already recorded its automatic creator membership for the (owner, executor) pair under the image bootstrap administrator.
4. The crashing connection authenticated directly as the executor, so session_user and current_user were both the synthetic executor; this was not a SET ROLE context. That session requested a second edge for the same pair with the executor as explicit grantor.

Only the two synthetic roles participated in the tested operation.

Minimal failing statement

GRANT synthetic_owner TO CURRENT_USER
  WITH ADMIN FALSE, INHERIT FALSE, SET TRUE
  GRANTED BY CURRENT_USER;

Expected result

The statement should return normally and record a second membership edge whose role is the synthetic owner, member and grantor are the synthetic executor, and options are ADMIN FALSE, INHERIT FALSE, SET TRUE. The existing automatic creator edge should remain unchanged.

Observed result

On both exact images, PostgreSQL 17 terminated the executing backend with signal 11 at the GRANT. The client observed an unexpected end of connection, the in-flight transaction aborted, and the server recovered to accept connections. No successful role switch, revoke, or positive second run followed the crash.

On .140, the equivalent statement without the explicit GRANTED BY clause was also tried once and terminated the backend with signal 11. This is corroborating evidence; the cross-image comparison above uses the unchanged explicit-grantor statement.

Privacy-bounded server log

server process ... was terminated by signal 11: Segmentation fault
terminating any other active server processes
database system was interrupted
database system is ready to accept connections

Questions

1. Is this role-membership crash a known Supabase Postgres issue?
2. What is the first exact Supabase Postgres image that contains a fix?
3. Which stable Supabase CLI release selects that image?
4. Is the fixed runtime available or eligible for hosted projects?
5. What additional privacy-bounded diagnostics would be required for triage? Any diagnostic rerun would require separate approval.

Reviewed artifact hashes

• Report: e2130dc770edf21548d1964468446c1cd8f877f531850fe3e468d3d3be128cc8
• Minimal SQL: bb9ef3993642b53e052533c7e09413e25589d7dd1f6b9ff8323cb802c0e838b1
• Bounded log: f9f8d06b053dfc26b2147755c8aabbb959a86d8cbbd885614d8eae9fbef7078f