Check if subject is equal to subject of id token when verifying JWT c…

…laims

Fixes jumbojett#406

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- Check subject when verifying JWT claims #406
+
 ### Fixed
 - Changed parameter #2 of http_build_query to empty string on requestTokenExchange to support PHP8.x #413
 - Return types are too strict. #412

src/OpenIDConnectClient.php

@@ -1206,6 +1206,7 @@ protected function verifyJWTClaims($claims, string $accessToken = null): bool
         }
         return (($this->validateIssuer($claims->iss))
             && (($claims->aud === $this->clientID) || in_array($this->clientID, $claims->aud, true))
+            && ($claims->sub === $this->getIdTokenPayload()->sub)
             && (!isset($claims->nonce) || $claims->nonce === $this->getNonce())
             && ( !isset($claims->exp) || ((is_int($claims->exp)) && ($claims->exp >= time() - $this->leeway)))
             && ( !isset($claims->nbf) || ((is_int($claims->nbf)) && ($claims->nbf <= time() + $this->leeway)))