diff --git a/lib/composer/composer/autoload_classmap.php b/lib/composer/composer/autoload_classmap.php
index aaf5602ba47e4..3e57d0bfb9cc6 100644
--- a/lib/composer/composer/autoload_classmap.php
+++ b/lib/composer/composer/autoload_classmap.php
@@ -922,6 +922,7 @@
     'OCP\\Server' => $baseDir . '/lib/public/Server.php',
     'OCP\\ServerVersion' => $baseDir . '/lib/public/ServerVersion.php',
     'OCP\\Session\\Exceptions\\SessionNotAvailableException' => $baseDir . '/lib/public/Session/Exceptions/SessionNotAvailableException.php',
+    'OCP\\Session\\ISessionIdRenewer' => $baseDir . '/lib/public/Session/ISessionIdRenewer.php',
     'OCP\\Settings\\DeclarativeSettingsTypes' => $baseDir . '/lib/public/Settings/DeclarativeSettingsTypes.php',
     'OCP\\Settings\\Events\\DeclarativeSettingsGetValueEvent' => $baseDir . '/lib/public/Settings/Events/DeclarativeSettingsGetValueEvent.php',
     'OCP\\Settings\\Events\\DeclarativeSettingsRegisterFormEvent' => $baseDir . '/lib/public/Settings/Events/DeclarativeSettingsRegisterFormEvent.php',
@@ -2357,6 +2358,7 @@
     'OC\\Session\\Internal' => $baseDir . '/lib/private/Session/Internal.php',
     'OC\\Session\\Memory' => $baseDir . '/lib/private/Session/Memory.php',
     'OC\\Session\\Session' => $baseDir . '/lib/private/Session/Session.php',
+    'OC\\Session\\SessionIdRenewer' => $baseDir . '/lib/private/Session/SessionIdRenewer.php',
     'OC\\Settings\\AuthorizedGroup' => $baseDir . '/lib/private/Settings/AuthorizedGroup.php',
     'OC\\Settings\\AuthorizedGroupMapper' => $baseDir . '/lib/private/Settings/AuthorizedGroupMapper.php',
     'OC\\Settings\\DeclarativeManager' => $baseDir . '/lib/private/Settings/DeclarativeManager.php',
diff --git a/lib/composer/composer/autoload_static.php b/lib/composer/composer/autoload_static.php
index d07e0aaa6b3bd..32aaf716ce4ef 100644
--- a/lib/composer/composer/autoload_static.php
+++ b/lib/composer/composer/autoload_static.php
@@ -963,6 +963,7 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OCP\\Server' => __DIR__ . '/../../..' . '/lib/public/Server.php',
         'OCP\\ServerVersion' => __DIR__ . '/../../..' . '/lib/public/ServerVersion.php',
         'OCP\\Session\\Exceptions\\SessionNotAvailableException' => __DIR__ . '/../../..' . '/lib/public/Session/Exceptions/SessionNotAvailableException.php',
+        'OCP\\Session\\ISessionIdRenewer' => __DIR__ . '/../../..' . '/lib/public/Session/ISessionIdRenewer.php',
         'OCP\\Settings\\DeclarativeSettingsTypes' => __DIR__ . '/../../..' . '/lib/public/Settings/DeclarativeSettingsTypes.php',
         'OCP\\Settings\\Events\\DeclarativeSettingsGetValueEvent' => __DIR__ . '/../../..' . '/lib/public/Settings/Events/DeclarativeSettingsGetValueEvent.php',
         'OCP\\Settings\\Events\\DeclarativeSettingsRegisterFormEvent' => __DIR__ . '/../../..' . '/lib/public/Settings/Events/DeclarativeSettingsRegisterFormEvent.php',
@@ -2398,6 +2399,7 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OC\\Session\\Internal' => __DIR__ . '/../../..' . '/lib/private/Session/Internal.php',
         'OC\\Session\\Memory' => __DIR__ . '/../../..' . '/lib/private/Session/Memory.php',
         'OC\\Session\\Session' => __DIR__ . '/../../..' . '/lib/private/Session/Session.php',
+        'OC\\Session\\SessionIdRenewer' => __DIR__ . '/../../..' . '/lib/private/Session/SessionIdRenewer.php',
         'OC\\Settings\\AuthorizedGroup' => __DIR__ . '/../../..' . '/lib/private/Settings/AuthorizedGroup.php',
         'OC\\Settings\\AuthorizedGroupMapper' => __DIR__ . '/../../..' . '/lib/private/Settings/AuthorizedGroupMapper.php',
         'OC\\Settings\\DeclarativeManager' => __DIR__ . '/../../..' . '/lib/private/Settings/DeclarativeManager.php',
diff --git a/lib/private/Server.php b/lib/private/Server.php
index 439974df99762..be395e89afe29 100644
--- a/lib/private/Server.php
+++ b/lib/private/Server.php
@@ -1036,6 +1036,7 @@ public function __construct(
 			$session = $c->get(IUserSession::class);
 			return $session->getSession();
 		}, false);
+		$this->registerAlias(\OCP\Session\ISessionIdRenewer::class, \OC\Session\SessionIdRenewer::class);
 
 		$this->registerAlias(IShareHelper::class, ShareHelper::class);
 		$this->registerAlias(IContactsStore::class, ContactsStore::class);
diff --git a/lib/private/Session/SessionIdRenewer.php b/lib/private/Session/SessionIdRenewer.php
new file mode 100644
index 0000000000000..1d9b241913a75
--- /dev/null
+++ b/lib/private/Session/SessionIdRenewer.php
@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OC\Session;
+
+use OC\Authentication\Token\IProvider;
+use OC\User\Session as UserSession;
+use OCP\Authentication\Exceptions\InvalidTokenException;
+use OCP\Session\ISessionIdRenewer;
+
+final readonly class SessionIdRenewer implements ISessionIdRenewer {
+	public function __construct(
+		private UserSession $userSession,
+		private IProvider $tokenProvider,
+	) {
+	}
+
+	#[\Override]
+	public function renewSessionId(): void {
+		$session = $this->userSession->getSession();
+		$oldId = $session->getId();
+		try {
+			$token = $this->tokenProvider->getToken($oldId);
+		} catch (InvalidTokenException) {
+			$token = null;
+		}
+
+		$session->regenerateId(true, false);
+		if ($token === null) {
+			return;
+		}
+
+		$this->tokenProvider->rotate($token, $oldId, $session->getId());
+		// No token has the old id any more; this drops it from the token cache.
+		$this->tokenProvider->invalidateToken($oldId);
+		$this->userSession->renewMagicSessionId($oldId);
+	}
+}
diff --git a/lib/public/Session/ISessionIdRenewer.php b/lib/public/Session/ISessionIdRenewer.php
new file mode 100644
index 0000000000000..f50e6a2320937
--- /dev/null
+++ b/lib/public/Session/ISessionIdRenewer.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCP\Session;
+
+use OCP\AppFramework\Attribute\Consumable;
+use OCP\Session\Exceptions\SessionNotAvailableException;
+
+/**
+ * Gives the current session a new id while it stays logged in, e.g. after
+ * the user proved their identity once more in this session.
+ *
+ * @since 36.0.0
+ */
+#[Consumable(since: '36.0.0')]
+interface ISessionIdRenewer {
+	/**
+	 * Renews the id of the current session. The old id stops working.
+	 *
+	 * The session keeps its auth token: the token keeps its id, name and
+	 * stored password and is moved to the new session id. A remember-me
+	 * cookie that points to the old session id is updated as well.
+	 *
+	 * @throws SessionNotAvailableException if there is no session
+	 * @since 36.0.0
+	 */
+	public function renewSessionId(): void;
+}
diff --git a/tests/lib/Session/SessionIdRenewerTest.php b/tests/lib/Session/SessionIdRenewerTest.php
new file mode 100644
index 0000000000000..db21077b7b9ce
--- /dev/null
+++ b/tests/lib/Session/SessionIdRenewerTest.php
@@ -0,0 +1,148 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace Test\Session;
+
+use OC\Authentication\Exceptions\InvalidTokenException;
+use OC\Authentication\Token\IProvider;
+use OC\Authentication\Token\PublicKeyToken;
+use OC\Authentication\Token\PublicKeyTokenProvider;
+use OC\Session\SessionIdRenewer;
+use OC\User\Session as UserSession;
+use OCP\Authentication\Token\IToken;
+use OCP\ISession;
+use OCP\Server;
+use OCP\Session\Exceptions\SessionNotAvailableException;
+use OCP\Session\ISessionIdRenewer;
+use PHPUnit\Framework\MockObject\MockObject;
+use Test\TestCase;
+
+#[\PHPUnit\Framework\Attributes\Group('DB')]
+final class SessionIdRenewerTest extends TestCase {
+	private const OLD_ID = 'old-session-id-0123456789abcdef';
+	private const NEW_ID = 'new-session-id-0123456789abcdef';
+
+	private UserSession&MockObject $userSession;
+	private ISession&MockObject $session;
+	private string $currentId = self::OLD_ID;
+
+	#[\Override]
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->currentId = self::OLD_ID;
+		$this->session = $this->createMock(ISession::class);
+		$this->session->method('getId')
+			->willReturnCallback(fn (): string => $this->currentId);
+		$this->userSession = $this->createMock(UserSession::class);
+		$this->userSession->method('getSession')
+			->willReturn($this->session);
+	}
+
+	#[\Override]
+	protected function tearDown(): void {
+		$provider = Server::get(PublicKeyTokenProvider::class);
+		$provider->invalidateToken(self::OLD_ID);
+		$provider->invalidateToken(self::NEW_ID);
+		parent::tearDown();
+	}
+
+	private function expectRegenerate(): void {
+		$this->session->expects($this->once())
+			->method('regenerateId')
+			->with(true, false)
+			->willReturnCallback(function (): void {
+				$this->currentId = self::NEW_ID;
+			});
+	}
+
+	public function testIsRegistered(): void {
+		$this->assertInstanceOf(SessionIdRenewer::class, Server::get(ISessionIdRenewer::class));
+	}
+
+	public function testKeepsTheTokenUnderTheNewId(): void {
+		$provider = Server::get(PublicKeyTokenProvider::class);
+		$token = $provider->generateToken(self::OLD_ID, 'renew-user', 'renew-login', 'secret password', 'Firefox', IToken::TEMPORARY_TOKEN, IToken::REMEMBER);
+		$this->expectRegenerate();
+		$this->userSession->expects($this->once())
+			->method('renewMagicSessionId')
+			->with(self::OLD_ID);
+
+		(new SessionIdRenewer($this->userSession, $provider))->renewSessionId();
+
+		$renewed = $provider->getToken(self::NEW_ID);
+		$this->assertSame($token->getId(), $renewed->getId());
+		$this->assertSame('Firefox', $renewed->getName());
+		$this->assertSame(IToken::REMEMBER, $renewed->getRemember());
+		$this->assertSame('secret password', $provider->getPassword($renewed, self::NEW_ID));
+		$this->expectException(InvalidTokenException::class);
+		$provider->getToken(self::OLD_ID);
+	}
+
+	public function testMovesTheTokenBeforeTheRememberMeCookie(): void {
+		$token = $this->createMock(PublicKeyToken::class);
+		$provider = $this->createMock(IProvider::class);
+		$provider->method('getToken')
+			->with(self::OLD_ID)
+			->willReturn($token);
+		$this->expectRegenerate();
+		$calls = [];
+		$provider->expects($this->once())
+			->method('rotate')
+			->with($token, self::OLD_ID, self::NEW_ID)
+			->willReturnCallback(function () use (&$calls, $token): PublicKeyToken {
+				$calls[] = 'rotate';
+				return $token;
+			});
+		$provider->expects($this->once())
+			->method('invalidateToken')
+			->with(self::OLD_ID)
+			->willReturnCallback(function () use (&$calls): void {
+				$calls[] = 'forget';
+			});
+		$this->userSession->expects($this->once())
+			->method('renewMagicSessionId')
+			->with(self::OLD_ID)
+			->willReturnCallback(function () use (&$calls): void {
+				$calls[] = 'cookie';
+			});
+
+		(new SessionIdRenewer($this->userSession, $provider))->renewSessionId();
+
+		$this->assertSame(['rotate', 'forget', 'cookie'], $calls);
+	}
+
+	public function testRenewsTheIdOfASessionWithoutToken(): void {
+		$provider = $this->createMock(IProvider::class);
+		$provider->method('getToken')
+			->willThrowException(new InvalidTokenException());
+		$this->expectRegenerate();
+		$provider->expects($this->never())->method('rotate');
+		$provider->expects($this->never())->method('invalidateToken');
+		$this->userSession->expects($this->never())->method('renewMagicSessionId');
+
+		(new SessionIdRenewer($this->userSession, $provider))->renewSessionId();
+
+		$this->assertSame(self::NEW_ID, $this->currentId);
+	}
+
+	public function testWithoutSessionNothingChanges(): void {
+		$session = $this->createMock(ISession::class);
+		$session->method('getId')
+			->willThrowException(new SessionNotAvailableException());
+		$session->expects($this->never())->method('regenerateId');
+		$userSession = $this->createMock(UserSession::class);
+		$userSession->method('getSession')->willReturn($session);
+		$provider = $this->createMock(IProvider::class);
+		$provider->expects($this->never())->method('rotate');
+
+		$this->expectException(SessionNotAvailableException::class);
+		(new SessionIdRenewer($userSession, $provider))->renewSessionId();
+	}
+}