Backport of:

From cb49e67303dbafbab1cebf4086e3ec15b7d56ee5 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Fri, 10 Mar 2023 09:22:43 +0100
Subject: [PATCH] url: only reuse connections with same GSS delegation

Reported-by: Harry Sintonen
Closes #10731
---
 lib/url.c     | 6 ++++++
 lib/urldata.h | 1 +
 2 files changed, 7 insertions(+)

--- a/lib/url.c
+++ b/lib/url.c
@@ -1233,6 +1233,11 @@ ConnectionExists(struct Curl_easy *data,
         }
       }
 
+      /* GSS delegation differences do not actually affect every connection
+         and auth method, but this check takes precaution before efficiency */
+      if(needle->gssapi_delegation != check->gssapi_delegation)
+        continue;
+
       if(get_protocol_family(needle->handler) & PROTO_FAMILY_SSH) {
         if(!ssh_config_matches(needle, check))
           continue;
@@ -1661,6 +1666,7 @@ static struct connectdata *allocate_conn
   conn->fclosesocket = data->set.fclosesocket;
   conn->closesocket_client = data->set.closesocket_client;
   conn->lastused = Curl_now(); /* used now */
+  conn->gssapi_delegation = data->set.gssapi_delegation;
 
   return conn;
   error:
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -1116,6 +1116,7 @@ struct connectdata {
 #ifdef USE_UNIX_SOCKETS
   char *unix_domain_socket;
 #endif
+  long gssapi_delegation; /* inherited from set.gssapi_delegation */
 };
 
 /* The end of connectdata. */