From 089afd78cb5897adf5a42d8ccff01d7c32c8fada Mon Sep 17 00:00:00 2001
From: Stefan Eissing <stefan@eissing.org>
Date: Mon, 6 Oct 2025 14:08:07 +0200
Subject: [PATCH] socks: handle premature close

When expecting to receive a number of bytes during socks connect,
treat an early connection close as error.

Reported-by: Joshua Rogers
Closes #18883
---
 lib/socks.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/socks.c b/lib/socks.c
index ba7b28d04a..e7e545442a 100644
--- a/lib/socks.c
+++ b/lib/socks.c
@@ -254,8 +254,14 @@ static CURLproxycode socks_recv(struct socks_state *sx,
             curl_easy_strerror(result));
       return CURLPX_RECV_CONNECT;
     }
-    else if(!nread) /* EOF */
+    else if(!nread) { /* EOF */
+      if(Curl_bufq_len(&sx->iobuf) < min_bytes) {
+        failf(data, "Failed to receive SOCKS response, "
+              "proxy closed connection");
+        return CURLPX_RECV_CONNECT;
+      }
       break;
+    }
   }
   *done = TRUE;
   return CURLPX_OK;
-- 
2.47.3