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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
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.