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help / color / mirror / Atom feedFrom: Noah Misch <noah@leadboat.com>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix unbounded recursive handling of SSL/GSS in ProcessStartupPac
Date: Mon, 11 May 2026 12:19:37 +0000
Message-ID: <E1wMPbl-0002U8-1D@gemulon.postgresql.org> (raw)
Fix unbounded recursive handling of SSL/GSS in ProcessStartupPacket()
The handling of SSL and GSS negotiation messages in
ProcessStartupPacket() could cause a recursion of the backend,
ultimately crashing the server as the negotiation attempts were not
tracked across multiple calls processing startup packets.
A malicious client could therefore alternate rejected SSL and GSS
requests indefinitely, each adding a stack frame, until the backend
crashed with a stack overflow, taking down a server.
This commit addresses this issue by modifying ProcessStartupPacket() so
as processed negotiation attempts are tracked, preventing infinite
recursive attempts. A TAP test is added to check this problem, where
multiple SSL and GSS negotiated attempts are stacked.
Reported-by: Calif.io in collaboration with Claude and Anthropic
Research
Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Security: CVE-2026-6479
Backpatch-through: 14
Branch
------
REL_18_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/f7a191f5377dacd05d22dd40c1d1e38b393ea9b4
Author: Michael Paquier <michael@paquier.xyz>
Modified Files
--------------
src/backend/tcop/backend_startup.c | 23 +++++++++-
src/test/postmaster/meson.build | 1 +
src/test/postmaster/t/004_negotiate.pl | 82 ++++++++++++++++++++++++++++++++++
3 files changed, 104 insertions(+), 2 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: noah@leadboat.com, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Fix unbounded recursive handling of SSL/GSS in ProcessStartupPac
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