diff --git a/application/Espo/Core/Record/Defaults/DefaultPopulator.php b/application/Espo/Core/Record/Defaults/DefaultPopulator.php
index ea8c8b447a..1a6b9384cc 100644
--- a/application/Espo/Core/Record/Defaults/DefaultPopulator.php
+++ b/application/Espo/Core/Record/Defaults/DefaultPopulator.php
@@ -33,11 +33,17 @@ use Espo\Core\Acl;
 use Espo\Core\Acl\Permission;
 use Espo\Core\Acl\Table as AclTable;
 use Espo\Core\Currency\ConfigDataProvider as CurrencyConfigDataProvider;
+use Espo\Core\Field\Link;
+use Espo\Core\Field\LinkMultiple;
+use Espo\Core\Field\LinkMultipleItem;
 use Espo\Core\Name\Field;
 use Espo\Core\ORM\Entity as CoreEntity;
 use Espo\Core\ORM\Type\FieldType;
 use Espo\Core\Utils\FieldUtil;
+use Espo\Core\Utils\Metadata;
 use Espo\Entities\User;
+use Espo\Modules\Crm\Entities\Account;
+use Espo\Modules\Crm\Entities\Contact;
 use Espo\ORM\Defs\Params\FieldParam;
 use Espo\ORM\Entity;
 use Espo\ORM\EntityManager;
@@ -54,6 +60,7 @@ class DefaultPopulator implements Populator
         private FieldUtil $fieldUtil,
         private EntityManager $entityManager,
         private CurrencyConfigDataProvider $currencyConfig,
+        private Metadata $metadata,
     ) {}
 
     public function populate(Entity $entity): void
@@ -61,6 +68,7 @@ class DefaultPopulator implements Populator
         $this->processAssignedUser($entity);
         $this->processDefaultTeam($entity);
         $this->processCurrency($entity);
+        $this->processPortal($entity);
     }
 
     /**
@@ -136,11 +144,11 @@ class DefaultPopulator implements Populator
         foreach ($this->fieldUtil->getEntityTypeFieldList($entityType) as $field) {
             $type = $this->fieldUtil->getEntityTypeFieldParam($entityType, $field, FieldParam::TYPE);
 
-            if (
-                $type === FieldType::CURRENCY &&
-                $entity->get($field) &&
-                !$entity->get($field . 'Currency')
-            ) {
+            if ($type !== FieldType::CURRENCY) {
+                continue;
+            }
+
+            if ($entity->get($field) && !$entity->get($field . 'Currency')) {
                 $entity->set($field . 'Currency', $this->currencyConfig->getDefaultCurrency());
             }
         }
@@ -180,4 +188,89 @@ class DefaultPopulator implements Populator
         $entity->set(Field::ASSIGNED_USER . 'Id', $this->user->getId());
         $entity->set(Field::ASSIGNED_USER . 'Name', $this->user->getName());
     }
+
+    private function processPortal(Entity $entity): void
+    {
+        if (!$this->user->isPortal()) {
+            return;
+        }
+
+        $this->processPortalAccount($entity);
+        $this->processPortalContact($entity);
+    }
+
+    private function processPortalAccount(Entity $entity): void
+    {
+        /** @var ?string $link */
+        $link = $this->metadata->get("aclDefs.{$entity->getEntityType()}.accountLink");
+
+        if (!$link) {
+            return;
+        }
+
+        $account = $this->user->getContact()?->getAccount();
+
+        if (!$account) {
+            return;
+        }
+
+        $this->processPortalRecord($entity, $link, $account);
+    }
+
+    private function processPortalContact(Entity $entity): void
+    {
+        /** @var ?string $link */
+        $link = $this->metadata->get("aclDefs.{$entity->getEntityType()}.contactLink");
+
+        if (!$link) {
+            return;
+        }
+
+        $contact = $this->user->getContact();
+
+        if (!$contact) {
+            return;
+        }
+
+        $this->processPortalRecord($entity, $link, $contact);
+    }
+
+    private function processPortalRecord(Entity $entity, string $link, Account|Contact $record): void
+    {
+        if (!$entity instanceof CoreEntity) {
+            return;
+        }
+
+        $fieldDefs = $this->entityManager
+            ->getDefs()
+            ->getEntity($entity->getEntityType())
+            ->tryGetField($link);
+
+        if (!$fieldDefs) {
+            return;
+        }
+
+        if (
+            $fieldDefs->getType() === FieldType::LINK ||
+            $fieldDefs->getType() === FieldType::LINK_ONE
+        ) {
+            if ($entity->has($link . 'Id')) {
+                return;
+            }
+
+            $entity->setValueObject($link, Link::create($record->getId(), $record->getName()));
+
+            return;
+        }
+
+        if ($fieldDefs->getType() === FieldType::LINK_MULTIPLE) {
+            if ($entity->has($link . 'Ids')) {
+                return;
+            }
+
+            $linkMultiple = LinkMultiple::create([LinkMultipleItem::create($record->getId(), $record->getName())]);
+
+            $entity->setValueObject($link, $linkMultiple);
+        }
+    }
 }
diff --git a/tests/integration/Espo/Record/DefaultsPopulatorTest.php b/tests/integration/Espo/Record/DefaultsPopulatorTest.php
new file mode 100644
index 0000000000..5212b4eef1
--- /dev/null
+++ b/tests/integration/Espo/Record/DefaultsPopulatorTest.php
@@ -0,0 +1,91 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM – Open Source CRM application.
+ * Copyright (C) 2014-2025 Yurii Kuznietsov, Taras Machyshyn, Oleksii Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU Affero General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU Affero General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace tests\integration\Espo\Record;
+
+use Espo\Core\Acl\Table;
+use Espo\Core\Exceptions\BadRequest;
+use Espo\Core\Exceptions\Conflict;
+use Espo\Core\Exceptions\Forbidden;
+use Espo\Core\Record\CreateParams;
+use Espo\Core\Record\ServiceContainer;
+use Espo\Entities\Portal;
+use Espo\Modules\Crm\Entities\Account;
+use Espo\Modules\Crm\Entities\CaseObj;
+use Espo\Modules\Crm\Entities\Contact;
+use tests\integration\Core\BaseTestCase;
+
+class DefaultsPopulatorTest extends BaseTestCase
+{
+    /**
+     * @throws BadRequest
+     * @throws Forbidden
+     * @throws Conflict
+     */
+    public function testPortal(): void
+    {
+        $em = $this->getEntityManager();
+
+        $account = $em->getRDBRepositoryByClass(Account::class)->getNew();
+        $em->saveEntity($account);
+
+        $contact = $em->getRDBRepositoryByClass(Contact::class)->getNew();
+        $contact->setAccount($account);
+        $em->saveEntity($contact);
+
+        $portal = $em->getRDBRepositoryByClass(Portal::class)->getNew();
+        $em->saveEntity($portal);
+
+        $this->createUser([
+            'userName' => 'tester',
+            'portalsIds' => [$portal->getId()],
+            'contactId' => $contact->getId(),
+            'accountsIds' => [$account->getId()],
+        ], [
+            'data' => [
+                'Case' => [
+                    'create' => Table::LEVEL_YES,
+                    'read' => 'contact',
+                ],
+            ],
+        ], true);
+
+        $this->auth('tester', null, $portal->getId());
+        $this->reCreateApplication();;
+
+        $service = $this->getContainer()->getByClass(ServiceContainer::class)->getByClass(CaseObj::class);
+
+        $case = $service->create((object) [
+            'name' => 'Test',
+        ], CreateParams::create());
+
+        $this->assertEquals($contact->getId(), $case->getContact()?->getId());
+        $this->assertEquals($account->getId(), $case->getAccount()?->getId());
+    }
+}