diff --git a/apps/files/lib/Sharing/Source/NodeShareSourceType.php b/apps/files/lib/Sharing/Source/NodeShareSourceType.php
index 3ebf9cd1626ec..cabaaf2089f18 100644
--- a/apps/files/lib/Sharing/Source/NodeShareSourceType.php
+++ b/apps/files/lib/Sharing/Source/NodeShareSourceType.php
@@ -57,6 +57,10 @@ public function getDisplayName(IFactory $l10nFactory): string {
 
 	#[\Override]
 	public function validateSource(string $source): bool {
+		if ((string)(int)$source !== $source) {
+			return false;
+		}
+
 		return $this->rootFolder->getFirstNodeById((int)$source) instanceof Node;
 	}
 
diff --git a/apps/files/tests/Sharing/Source/NodeShareSourceTypeTest.php b/apps/files/tests/Sharing/Source/NodeShareSourceTypeTest.php
index bb04d80af93a3..5b94af3e8dc7b 100644
--- a/apps/files/tests/Sharing/Source/NodeShareSourceTypeTest.php
+++ b/apps/files/tests/Sharing/Source/NodeShareSourceTypeTest.php
@@ -77,6 +77,9 @@ protected function tearDown(): void {
 	public function testValidateSource(): void {
 		$this->assertTrue($this->sourceType->validateSource((string)$this->node->getId()));
 		$this->assertFalse($this->sourceType->validateSource('-1'));
+		$this->assertFalse($this->sourceType->validateSource('000123'));
+		$this->assertFalse($this->sourceType->validateSource('123abcdef'));
+		$this->assertFalse($this->sourceType->validateSource('000123abcdef'));
 	}
 
 	public function testGetSourceDisplayName(): void {