diff --git a/NEWS b/NEWS
index 2639e8a715c..c6bc1e5602d 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,10 @@ PHP                                                                        NEWS
   . Fixed imagecrop() overflow with rect argument with x/width y/heigh usage
     in gdImageCrop(). (David Carlier)
 
+- OpenSSL:
+  . Fix memory leak in openssl_sign() when passing invalid algorithm.
+    (nielsdos)
+
 - Standard:
   . Fixed bug GH-18145 (php8ts crashes in php_clear_stat_cache()).
     (Jakub Zelenka)
diff --git a/ext/openssl/openssl.c b/ext/openssl/openssl.c
index be68216b524..e4bd00d23e0 100644
--- a/ext/openssl/openssl.c
+++ b/ext/openssl/openssl.c
@@ -7162,6 +7162,7 @@ PHP_FUNCTION(openssl_sign)
 		mdtype = php_openssl_get_evp_md_from_algo(method_long);
 	}
 	if (!mdtype && (!can_default_digest || method_long != 0)) {
+		EVP_PKEY_free(pkey);
 		php_error_docref(NULL, E_WARNING, "Unknown digest algorithm");
 		RETURN_FALSE;
 	}
diff --git a/ext/openssl/tests/openssl_sign_invalid_algorithm.phpt b/ext/openssl/tests/openssl_sign_invalid_algorithm.phpt
new file mode 100644
index 00000000000..c669a373a10
--- /dev/null
+++ b/ext/openssl/tests/openssl_sign_invalid_algorithm.phpt
@@ -0,0 +1,18 @@
+--TEST--
+openssl_sign: invalid algorithm
+--EXTENSIONS--
+openssl
+--FILE--
+<?php
+$dir = __DIR__;
+$file_pub = $dir . '/bug37820cert.pem';
+$file_key = $dir . '/bug37820key.pem';
+
+$priv_key = file_get_contents($file_key);
+$priv_key_id = openssl_get_privatekey($priv_key);
+
+$data = "some custom data";
+openssl_sign($data, $signature, $priv_key_id, "invalid algo");
+?>
+--EXPECTF--
+Warning: openssl_sign(): Unknown digest algorithm in %s on line %d