diff --git a/ssh-agent.c b/ssh-agent.c
index 618bb198..8ea831f4 100644
diff -up openssh-9.3p1/ssh-agent.c.cve openssh-9.3p1/ssh-agent.c
--- openssh-9.3p1/ssh-agent.c.cve	2023-07-21 15:38:13.237276580 +0200
+++ openssh-9.3p1/ssh-agent.c	2023-07-21 15:41:30.269943569 +0200
@@ -169,6 +169,12 @@ char socket_dir[PATH_MAX];
 /* Pattern-list of allowed PKCS#11/Security key paths */
 static char *allowed_providers;
 
+/*
+ * Allows PKCS11 providers or SK keys that use non-internal providers to
+ * be added over a remote connection (identified by session-bind@openssh.com).
+ */
+static int remote_add_provider;
+
 /* locking */
 #define LOCK_SIZE	32
 #define LOCK_SALT_SIZE	16
@@ -1228,6 +1234,12 @@ process_add_identity(SocketEntry *e)
 		if (strcasecmp(sk_provider, "internal") == 0) {
 			debug_f("internal provider");
 		} else {
+			if (e->nsession_ids != 0 && !remote_add_provider) {
+				verbose("failed add of SK provider \"%.100s\": "
+				    "remote addition of providers is disabled",
+				    sk_provider);
+				goto out;
+			}
 			if (realpath(sk_provider, canonical_provider) == NULL) {
 				verbose("failed provider \"%.100s\": "
 				    "realpath: %s", sk_provider,
@@ -1368,7 +1380,7 @@ no_identities(SocketEntry *e)
 
 #ifdef ENABLE_PKCS11
 static char *
-sanitize_pkcs11_provider(const char *provider)
+sanitize_pkcs11_provider(SocketEntry *e, const char *provider)
 {
 	struct pkcs11_uri *uri = NULL;
 	char *sane_uri, *module_path = NULL; /* default path */
@@ -1399,6 +1411,11 @@ sanitize_pkcs11_provider(const char *pro
 		module_path = strdup(provider); /* simple path */
 
 	if (module_path != NULL) { /* do not validate default NULL path in URI */
+		if (e->nsession_ids != 0 && !remote_add_provider) {
+			verbose("failed PKCS#11 add of \"%.100s\": remote addition of "
+			    "providers is disabled", provider);
+			return NULL;
+		}
 		if (realpath(module_path, canonical_provider) == NULL) {
 			verbose("failed PKCS#11 provider \"%.100s\": realpath: %s",
 			    module_path, strerror(errno));
@@ -1455,7 +1472,7 @@ process_add_smartcard_key(SocketEntry *e
 		goto send;
 	}
 
-	sane_uri = sanitize_pkcs11_provider(provider);
+	sane_uri = sanitize_pkcs11_provider(e, provider);
 	if (sane_uri == NULL)
 		goto send;
 
@@ -1516,7 +1533,7 @@ process_remove_smartcard_key(SocketEntry
 	}
 	free(pin);
 
-	sane_uri = sanitize_pkcs11_provider(provider);
+	sane_uri = sanitize_pkcs11_provider(e, provider);
 	if (sane_uri == NULL)
 		goto send;
 
@@ -2108,7 +2125,9 @@ main(int ac, char **av)
 			break;
 		case 'O':
 			if (strcmp(optarg, "no-restrict-websafe") == 0)
-				restrict_websafe  = 0;
+				restrict_websafe = 0;
+			else if (strcmp(optarg, "allow-remote-pkcs11") == 0)
+				remote_add_provider = 1;
 			else
 				fatal("Unknown -O option");
 			break;
diff --git a/ssh-pkcs11.c b/ssh-pkcs11.c
index 6be647ec..ebddf6c3 100644
--- a/ssh-pkcs11.c
+++ b/ssh-pkcs11.c
@@ -1537,10 +1537,8 @@ pkcs11_register_provider(char *provider_id, char *pin,
 		error("dlopen %s failed: %s", provider_module, dlerror());
 		goto fail;
 	}
-	if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL) {
-		error("dlsym(C_GetFunctionList) failed: %s", dlerror());
-		goto fail;
-	}
+	if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL)
+		fatal("dlsym(C_GetFunctionList) failed: %s", dlerror());
 
 	p->module->handle = handle;
 	/* setup the pkcs11 callbacks */
--- a/ssh-agent.1	2023-03-15 22:28:19.000000000 +0100
+++ b/ssh-agent.1	2023-07-19 21:39:17.981406432 +0200
@@ -107,9 +107,27 @@
 .It Fl O Ar option
 Specify an option when starting
 .Nm .
-Currently only one option is supported:
+Currently two options are supported:
+.Cm allow-remote-pkcs11
+and
 .Cm no-restrict-websafe .
-This instructs
+.Pp
+The
+.Cm allow-remote-pkcs11
+option allows clients of a forwarded
+.Nm
+to load PKCS#11 or FIDO provider libraries.
+By default only local clients may perform this operation.
+Note that signalling that a
+.Nm
+client remote is performed by
+.Xr ssh 1 ,
+and use of other tools to forward access to the agent socket may circumvent
+this restriction.
+.Pp
+The
+.Cm no-restrict-websafe ,
+instructs
 .Nm
 to permit signatures using FIDO keys that might be web authentication
 requests.