diff --git a/apps/files/lib/Capabilities.php b/apps/files/lib/Capabilities.php
index dc2aae6acfcd9..54b57aed0745d 100644
--- a/apps/files/lib/Capabilities.php
+++ b/apps/files/lib/Capabilities.php
@@ -39,13 +39,14 @@ public function __construct(IConfig $config) {
 	/**
 	 * Return this classes capabilities
 	 *
-	 * @return array{files: array{bigfilechunking: bool, blacklisted_files: array<mixed>}}
+	 * @return array{files: array{bigfilechunking: bool, blacklisted_files: array<mixed>, forbidden_filename_characters: array<string>}}
 	 */
 	public function getCapabilities() {
 		return [
 			'files' => [
 				'bigfilechunking' => true,
-				'blacklisted_files' => (array)$this->config->getSystemValue('blacklisted_files', ['.htaccess'])
+				'blacklisted_files' => (array)$this->config->getSystemValue('blacklisted_files', ['.htaccess']),
+				'forbidden_filename_characters' => \OC_Util::getForbiddenFileNameChars(),
 			],
 		];
 	}
diff --git a/apps/files/openapi.json b/apps/files/openapi.json
index f9432f6c57cd1..f9cdb67783d78 100644
--- a/apps/files/openapi.json
+++ b/apps/files/openapi.json
@@ -31,6 +31,7 @@
                         "required": [
                             "bigfilechunking",
                             "blacklisted_files",
+                            "forbidden_filename_characters",
                             "directEditing"
                         ],
                         "properties": {
@@ -43,6 +44,12 @@
                                     "type": "object"
                                 }
                             },
+                            "forbidden_filename_characters": {
+                                "type": "array",
+                                "items": {
+                                    "type": "string"
+                                }
+                            },
                             "directEditing": {
                                 "type": "object",
                                 "required": [
diff --git a/config/config.sample.php b/config/config.sample.php
index d999b1e39b0b0..79f813a4daec2 100644
--- a/config/config.sample.php
+++ b/config/config.sample.php
@@ -1962,6 +1962,8 @@
 /**
  * Blacklist characters from being used in filenames. This is useful if you
  * have a filesystem or OS which does not support certain characters like windows.
+ * 
+ * The '/' and '\' characters are always forbidden.
  *
  * Example for windows systems: ``array('?', '<', '>', ':', '*', '|', '"', chr(0), "\n", "\r")``
  * see https://en.wikipedia.org/wiki/Comparison_of_file_systems#Limits