diff --git a/com.woltlab.wcf/templates/email_lostPassword.tpl b/com.woltlab.wcf/templates/email_lostPassword.tpl
index e8aba2978e..d21bebe78e 100644
--- a/com.woltlab.wcf/templates/email_lostPassword.tpl
+++ b/com.woltlab.wcf/templates/email_lostPassword.tpl
@@ -7,7 +7,7 @@
 	{lang}wcf.user.lostPassword.mail.html.intro{/lang}
 
 	{capture assign=button}
-	<a href="{link controller='NewPassword' object=$mailbox->getUser() isHtmlEmail=true}k={$mailbox->getUser()->lostPasswordKey}{/link}">
+	<a href="{link controller='NewPassword' object=$mailbox->getUser() isHtmlEmail=true}k={$lostPasswordKey}{/link}">
 		{lang}wcf.user.lostPassword.mail.html.reset{/lang}
 	</a>
 	{/capture}
diff --git a/com.woltlab.wcf/templates/email_sendNewPassword.tpl b/com.woltlab.wcf/templates/email_sendNewPassword.tpl
index 1a96db9c68..6f57c7be21 100644
--- a/com.woltlab.wcf/templates/email_sendNewPassword.tpl
+++ b/com.woltlab.wcf/templates/email_sendNewPassword.tpl
@@ -7,7 +7,7 @@
 	{lang}wcf.acp.user.sendNewPassword.mail.html.intro{/lang}
 
 	{capture assign=button}
-	<a href="{link controller='NewPassword' object=$mailbox->getUser() isHtmlEmail=true}k={$mailbox->getUser()->lostPasswordKey}{/link}">
+	<a href="{link controller='NewPassword' object=$mailbox->getUser() isHtmlEmail=true}k={$lostPasswordKey}{/link}">
 		{lang}wcf.acp.user.sendNewPassword.mail.html.reset{/lang}
 	</a>
 	{/capture}
diff --git a/wcfsetup/install/files/acp/database/update_com.woltlab.wcf_6.3_step1.php b/wcfsetup/install/files/acp/database/update_com.woltlab.wcf_6.3_step1.php
index dc17365b4d..652ee94424 100644
--- a/wcfsetup/install/files/acp/database/update_com.woltlab.wcf_6.3_step1.php
+++ b/wcfsetup/install/files/acp/database/update_com.woltlab.wcf_6.3_step1.php
@@ -8,6 +8,7 @@
  * @license   GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  */
 
+use wcf\system\database\table\column\CharDatabaseTableColumn;
 use wcf\system\database\table\column\DefaultFalseBooleanDatabaseTableColumn;
 use wcf\system\database\table\column\JsonDatabaseTableColumn;
 use wcf\system\database\table\column\MediumintDatabaseTableColumn;
@@ -62,4 +63,9 @@
             NotNullVarchar255DatabaseTableColumn::create('emoji')
                 ->defaultValue(''),
         ]),
+    PartialDatabaseTable::create('wcf1_user')
+        ->columns([
+            CharDatabaseTableColumn::create('lostPasswordKey')
+                ->length(64),
+        ]),
 ];
diff --git a/wcfsetup/install/files/lib/data/user/User.class.php b/wcfsetup/install/files/lib/data/user/User.class.php
index 5c921ceb46..c54510fd44 100644
--- a/wcfsetup/install/files/lib/data/user/User.class.php
+++ b/wcfsetup/install/files/lib/data/user/User.class.php
@@ -40,7 +40,7 @@
  * @property-read   int     $activationCode         flag which determines, whether the user is activated (for legacy reasons an random integer, if the user is *not* activated)
  * @property-read   ?string $emailConfirmed         code sent to the user's email address used for account activation or null if the email is confirmed
  * @property-read   int     $lastLostPasswordRequestTime    timestamp at which the user has reported that they lost their password or 0 if password has not been reported as lost
- * @property-read   ?string $lostPasswordKey        code used for authenticating setting new password after password loss or empty if password has not been reported as lost
+ * @property-read   ?string $lostPasswordKey        SHA-256 hash of the code used for authenticating setting new password after password loss or empty if password has not been reported as lost
  * @property-read   int     $lastUsernameChange     timestamp at which the user changed their name the last time or 0 if username has not been changed
  * @property-read   string  $newEmail               new email address of the user that has to be manually confirmed or empty if no new email address has been set
  * @property-read   string  $oldUsername            previous name of the user or empty if they have had no previous name
diff --git a/wcfsetup/install/files/lib/form/LostPasswordForm.class.php b/wcfsetup/install/files/lib/form/LostPasswordForm.class.php
index f1532c1479..440d23671e 100644
--- a/wcfsetup/install/files/lib/form/LostPasswordForm.class.php
+++ b/wcfsetup/install/files/lib/form/LostPasswordForm.class.php
@@ -158,10 +158,10 @@ public function save()
         // generate a new lost password key
         $lostPasswordKey = Hex::encode(\random_bytes(20));
 
-        // save key and request time in database
+        // save hashed key and request time in database
         $this->objectAction = new UserAction([$this->user], 'update', [
             'data' => \array_merge($this->additionalFields, [
-                'lostPasswordKey' => $lostPasswordKey,
+                'lostPasswordKey' => \hash('sha256', $lostPasswordKey),
                 'lastLostPasswordRequestTime' => \TIME_NOW,
             ]),
         ]);
@@ -174,8 +174,8 @@ public function save()
         $email->addRecipient(new UserMailbox($this->user));
         $email->setSubject($this->user->getLanguage()->getDynamicVariable('wcf.user.lostPassword.mail.subject'));
         $email->setBody(new MimePartFacade([
-            new RecipientAwareTextMimePart('text/html', 'email_lostPassword'),
-            new RecipientAwareTextMimePart('text/plain', 'email_lostPassword'),
+            new RecipientAwareTextMimePart('text/html', 'email_lostPassword', 'wcf', ['lostPasswordKey' => $lostPasswordKey]),
+            new RecipientAwareTextMimePart('text/plain', 'email_lostPassword', 'wcf', ['lostPasswordKey' => $lostPasswordKey]),
         ]));
         $email->send();
 
diff --git a/wcfsetup/install/files/lib/form/NewPasswordForm.class.php b/wcfsetup/install/files/lib/form/NewPasswordForm.class.php
index 69c5b4866a..30fdd546d6 100644
--- a/wcfsetup/install/files/lib/form/NewPasswordForm.class.php
+++ b/wcfsetup/install/files/lib/form/NewPasswordForm.class.php
@@ -56,7 +56,7 @@ public function readParameters()
             if (!$this->user->lostPasswordKey) {
                 $this->throwInvalidLinkException();
             }
-            if (!\hash_equals($this->user->lostPasswordKey, $this->lostPasswordKey)) {
+            if (!\hash_equals($this->user->lostPasswordKey, \hash('sha256', $this->lostPasswordKey))) {
                 $this->throwInvalidLinkException();
             }
             // expire lost password requests after a day
@@ -66,7 +66,7 @@ public function readParameters()
 
             WCF::getSession()->register('lostPasswordRequest', [
                 'userID' => $this->user->userID,
-                'key' => $this->user->lostPasswordKey,
+                'key' => $this->lostPasswordKey,
             ]);
         } else {
             if (!\is_array(WCF::getSession()->getVar('lostPasswordRequest'))) {
@@ -78,7 +78,7 @@ public function readParameters()
             if (!$this->user->userID) {
                 throw new IllegalLinkException();
             }
-            if (!\hash_equals($this->user->lostPasswordKey, WCF::getSession()->getVar('lostPasswordRequest')['key'])) {
+            if (!\hash_equals($this->user->lostPasswordKey, \hash('sha256', WCF::getSession()->getVar('lostPasswordRequest')['key']))) {
                 $this->throwInvalidLinkException();
             }
         }
diff --git a/wcfsetup/install/files/lib/system/worker/SendNewPasswordWorker.class.php b/wcfsetup/install/files/lib/system/worker/SendNewPasswordWorker.class.php
index 0ce7518ec3..bde3504904 100644
--- a/wcfsetup/install/files/lib/system/worker/SendNewPasswordWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/SendNewPasswordWorker.class.php
@@ -32,6 +32,11 @@ class SendNewPasswordWorker extends AbstractWorker
      */
     protected $limit = 20;
 
+    /**
+     * @var array<int, string>
+     */
+    private array $lostPasswordKeys = [];
+
     #[\Override]
     public function countObjects()
     {
@@ -104,11 +109,13 @@ protected function resetPassword(UserEditor $userEditor)
         $userAction = new UserAction([$userEditor], 'update', [
             'data' => [
                 'password' => null,
-                'lostPasswordKey' => $lostPasswordKey,
+                'lostPasswordKey' => \hash('sha256', $lostPasswordKey),
                 'lastLostPasswordRequestTime' => $lastLostPasswordRequestTime,
             ],
         ]);
         $userAction->executeAction();
+
+        $this->lostPasswordKeys[$userEditor->userID] = $lostPasswordKey;
     }
 
     /**
@@ -128,9 +135,10 @@ protected function sendLink(User $user)
         ));
         $email->addRecipient(new UserMailbox($user));
         $email->setSubject($user->getLanguage()->getDynamicVariable('wcf.acp.user.sendNewPassword.mail.subject'));
+        $lostPasswordKey = $this->lostPasswordKeys[$user->userID] ?? '';
         $email->setBody(new MimePartFacade([
-            new RecipientAwareTextMimePart('text/html', 'email_sendNewPassword'),
-            new RecipientAwareTextMimePart('text/plain', 'email_sendNewPassword'),
+            new RecipientAwareTextMimePart('text/html', 'email_sendNewPassword', 'wcf', ['lostPasswordKey' => $lostPasswordKey]),
+            new RecipientAwareTextMimePart('text/plain', 'email_sendNewPassword', 'wcf', ['lostPasswordKey' => $lostPasswordKey]),
         ]));
         $jobs = $email->getJobs();
         foreach ($jobs as $job) {
diff --git a/wcfsetup/install/lang/de.xml b/wcfsetup/install/lang/de.xml
index d016a8a20b..5d309aed30 100644
--- a/wcfsetup/install/lang/de.xml
+++ b/wcfsetup/install/lang/de.xml
@@ -3215,7 +3215,7 @@ erforderlich, dass {if LANGUAGE_USE_INFORMAL_VARIANT}du{else}Sie{/if} ein neues
 Benutzerkonto {@$mailbox->getUser()->username} auf der Seite {@PAGE_TITLE|phrase} [URL:{link isEmail=true}{/link}]
 weiterhin verwenden {if LANGUAGE_USE_INFORMAL_VARIANT}kannst{else}können{/if}:
 
-    {link controller='NewPassword' object=$mailbox->getUser() isEmail=true}k={@$mailbox->getUser()->lostPasswordKey}{/link} {* this line ends with a space *}
+    {link controller='NewPassword' object=$mailbox->getUser() isEmail=true}k={@$lostPasswordKey}{/link} {* this line ends with a space *}
 
 {if LANGUAGE_USE_INFORMAL_VARIANT}Solltest du{else}Sollten Sie{/if} diese Nachricht erst nach dem {@$mailbox->getUser()->lastLostPasswordRequestTime+86400|plainTime} lesen, ist es
 aus Sicherheitsgründen erforderlich, dass {if LANGUAGE_USE_INFORMAL_VARIANT}du{else}Sie{/if} die Kennwort vergessen-Funktion [URL:{link controller='LostPassword' isEmail=true}{/link}] {if LANGUAGE_USE_INFORMAL_VARIANT}nutzt{else}nutzen{/if}.]]></item>
@@ -4607,7 +4607,7 @@ Erlaubte Dateiendungen: gif, jpg, jpeg, png, webp]]></item>
 {@$mailbox->getUser()->username} auf der Seite {@PAGE_TITLE|phrase} [URL:{link isEmail=true}{/link}] vergessen zu haben. {if LANGUAGE_USE_INFORMAL_VARIANT}Du kannst dein{else}Sie können Ihr{/if} Kennwort
 nach einem Klick auf den folgenden Link ändern:
 
-    {link controller='NewPassword' object=$mailbox->getUser() isEmail=true}k={@$mailbox->getUser()->lostPasswordKey}{/link} {* this line ends with a space *}
+    {link controller='NewPassword' object=$mailbox->getUser() isEmail=true}k={@$lostPasswordKey}{/link} {* this line ends with a space *}
 
 Wenn {if LANGUAGE_USE_INFORMAL_VARIANT}du dein{else}Sie Ihr{/if} Kennwort nicht ändern {if LANGUAGE_USE_INFORMAL_VARIANT}möchtest{else}möchten{/if}, dann wird diese Anfrage
 am {@$mailbox->getUser()->lastLostPasswordRequestTime+86400|plainTime} automatisch ablaufen.]]></item>
diff --git a/wcfsetup/install/lang/en.xml b/wcfsetup/install/lang/en.xml
index d5766cefdd..055e65c046 100644
--- a/wcfsetup/install/lang/en.xml
+++ b/wcfsetup/install/lang/en.xml
@@ -3142,7 +3142,7 @@ If you have <strong>already bought the licenses for the listed apps</strong>, th
 An administrator has reset your password. You are now required to set a new password to be able to use your
 user account {@$mailbox->getUser()->username} on the website {@PAGE_TITLE|phrase} [URL:{link isEmail=true}{/link}] again:
 
-    {link controller='NewPassword' object=$mailbox->getUser() isEmail=true}k={@$mailbox->getUser()->lostPasswordKey}{/link} {* this line ends with a space *}
+    {link controller='NewPassword' object=$mailbox->getUser() isEmail=true}k={@$lostPasswordKey}{/link} {* this line ends with a space *}
 
 If you read this message after {@$mailbox->getUser()->lastLostPasswordRequestTime+86400|plainTime} you’ll have to use
 the lost password form [URL:{link controller='LostPassword' isEmail=true}{/link}] for security reasons.]]></item>
@@ -4606,7 +4606,7 @@ You (or someone else) claimed to have lost the password for the user account {@$
 the website {@PAGE_TITLE|phrase} [URL:{link isEmail=true}{/link}]. You can change your password after clicking
 the following link:
 
-    {link controller='NewPassword' object=$mailbox->getUser() isEmail=true}k={@$mailbox->getUser()->lostPasswordKey}{/link} {* this line ends with a space *}
+    {link controller='NewPassword' object=$mailbox->getUser() isEmail=true}k={@$lostPasswordKey}{/link} {* this line ends with a space *}
 
 If you don’t want to change your password you can simply wait. The request will expire at {@$mailbox->getUser()->lastLostPasswordRequestTime+86400|plainTime}.]]></item>
 		<item name="wcf.user.lostPassword.mail.html.headline"><![CDATA[Dear {$mailbox->getUser()->username},]]></item>
diff --git a/wcfsetup/setup/db/install_com.woltlab.wcf.php b/wcfsetup/setup/db/install_com.woltlab.wcf.php
index 6b40769b76..c288809281 100644
--- a/wcfsetup/setup/db/install_com.woltlab.wcf.php
+++ b/wcfsetup/setup/db/install_com.woltlab.wcf.php
@@ -3786,7 +3786,7 @@
             NotNullInt10DatabaseTableColumn::create('lastLostPasswordRequestTime')
                 ->defaultValue(0),
             CharDatabaseTableColumn::create('lostPasswordKey')
-                ->length(40),
+                ->length(64),
             NotNullInt10DatabaseTableColumn::create('lastUsernameChange')
                 ->defaultValue(0),
             NotNullVarchar255DatabaseTableColumn::create('newEmail')