From 3957f136e2ed23caf176a594b54b3827f5cef701 Mon Sep 17 00:00:00 2001
From: Alexander Sosedkin <asosedkin@redhat.com>
Date: Wed, 18 Mar 2026 18:19:06 +0100
Subject: pkcs11_write: fix UAF and leak in gnutls_pkcs11_token_set_pin

Changing Security Officer PIN with gnutls_pkcs11_token_set_pin() with
oldpin == NULL for a token that lacks a protected authentication path
led to a use-after-free.

Reported-by: Luigino Camastra and Joshua Rogers of AISLE Research Team
Fixes: #1766
Fixes: #1809
Fixes: CVE-2026-42014
Fixes: GNUTLS-SA-2026-04-29-9
CVSS: 4.0 Medium CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Signed-off-by: Alexander Sosedkin <asosedkin@redhat.com>
---
 lib/pkcs11_write.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Index: gnutls-3.8.10/lib/pkcs11_write.c
===================================================================
--- gnutls-3.8.10.orig/lib/pkcs11_write.c
+++ gnutls-3.8.10/lib/pkcs11_write.c
@@ -1266,10 +1266,9 @@ int gnutls_pkcs11_token_set_pin(const ch
 		ses_flags = SESSION_WRITE | SESSION_LOGIN;
 
 	ret = pkcs11_open_session(&sinfo, NULL, info, ses_flags);
-	p11_kit_uri_free(info);
-
 	if (ret < 0) {
 		gnutls_assert();
+		p11_kit_uri_free(info);
 		return ret;
 	}
 
@@ -1290,9 +1289,11 @@ int gnutls_pkcs11_token_set_pin(const ch
 		oldpin_size = L(oldpin);
 
 		if (!(sinfo.tinfo.flags & CKF_PROTECTED_AUTHENTICATION_PATH)) {
-			if (newpin == NULL)
-				return gnutls_assert_val(
+			if (newpin == NULL) {
+				ret = gnutls_assert_val(
 					GNUTLS_E_INVALID_REQUEST);
+				goto finish;
+			}
 
 			if (oldpin == NULL) {
 				struct pin_info_st pin_info;
@@ -1324,6 +1325,7 @@ int gnutls_pkcs11_token_set_pin(const ch
 	ret = 0;
 
 finish:
+	p11_kit_uri_free(info);
 	pkcs11_close_session(&sinfo);
 	return ret;
 }
