postgres.git / summary / log / commit / refs

commit    067a64d40f92e4e012db0367f9ff2d2ae45671ca
Author:   Michael Paquier <michael@paquier.xyz>
Commit:   Noah Misch <noah@leadboat.com>
Date:     Mon Aug 10 13:38:18 2026 +0000
First released in: 17.11, 18.6

    Reject GSSEncRequest after direct SSL connection
    
    When a direct SSL connection was established, ProcessStartupPacket()
    still accepted GSSEncRequest messages.  The GSSAPI negotiation would
    then use raw writes and reads, bypassing the TLS encryption layer.
    After the GSS encryption was established, the connection continued to
    use TLS.  This could betray the HBA rules so as the backend does
    protocol exchanges inconsistent with the connection policies in place,
    with TLS taking priority over GSS in the backend.
    
    The SSL negotiation path already guarded against attempts to request
    SSL after a direct SSL request has been processed.  The GSS path is now
    guarded the same way when receiving a startup packet.
    
    Reported-by: p4p3r <kbfanta@naver.com>
    Author: Michael Paquier <michael@paquier.xyz>
    Reviewed-by: Jacob Champion <champion.p@gmail.com>
    Backpatch-through: 17
    Security: CVE-2026-14681


 src/backend/tcop/backend_startup.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/backend/tcop/backend_startup.c b/src/backend/tcop/backend_startup.c
index 2fe67015e3b..4dd4d35e6b4 100644
--- a/src/backend/tcop/backend_startup.c
+++ b/src/backend/tcop/backend_startup.c
@@ -625,8 +625,13 @@ retry:
 		char		GSSok = 'N';
 
 #ifdef ENABLE_GSS
-		/* No GSSAPI encryption when on Unix socket */
-		if (port->laddr.addr.ss_family != AF_UNIX)
+
+		/*
+		 * No GSSAPI encryption when on Unix socket.
+		 *
+		 * Also no GSS negotiation if we already have a direct SSL connection.
+		 */
+		if (port->laddr.addr.ss_family != AF_UNIX && !port->ssl_in_use)
 			GSSok = 'G';
 #endif
 


[parent: c3c830272a97]