fix: normalize string values and keys in ContentSecurityPolicy::addOption()

system/HTTP/ContentSecurityPolicy.php

@@ -878,14 +878,34 @@ protected function addOption($options, string $target, ?bool $explicitReporting
     {
         // Ensure we have an array to work with...
         if (is_string($this->{$target})) {
-            $this->{$target} = [$this->{$target} => $this->reportOnly];
+            $targetValue = trim($this->{$target});
+
+            $this->{$target} = [];
+
+            if ($targetValue !== '') {
+                foreach (preg_split('/\s+/', $targetValue) as $opt) {
+                    $this->{$target}[$opt] = $this->reportOnly;
+                }
+            }
+        } elseif (! is_array($this->{$target})) {
+            $this->{$target} = [];
         }
 
         $options = is_array($options) ? $options : [$options];
 
         foreach ($options as $option) {
+            $option = (string) $option;
+
+            if ($option === '' && $target !== 'sandbox') {
+                continue;
+            }
+
             $this->{$target}[$option] = $explicitReporting ?? $this->reportOnly;
         }
+
+        if ($target === 'sandbox' && count($this->{$target}) > 1 && isset($this->{$target}[''])) {
+            unset($this->{$target}['']);
+        }
     }
 
     /**
@@ -1013,13 +1033,25 @@ protected function buildHeaders(ResponseInterface $response)
     protected function addToHeader(string $name, $values = null)
     {
         if (is_string($values)) {
-            $values = [$values => $this->reportOnly];
+            $valueStr = trim($values);
+
+            if ($valueStr === '') {
+                return;
+            }
+
+            $values = [];
+
+            foreach (preg_split('/\s+/', $valueStr) as $val) {
+                $values[$val] = $this->reportOnly;
+            }
         }
 
         $sources       = [];
         $reportSources = [];
 
         foreach ($values as $value => $reportOnly) {
+            $value = (string) $value;
+
             if (
                 in_array($value, $this->validSources, true)
                 || str_starts_with($value, 'nonce-')

tests/system/HTTP/ContentSecurityPolicyTest.php

@@ -756,6 +756,70 @@ public function testSandboxFlags(): void
         $this->assertContains('sandbox allow-popups allow-top-navigation', $this->getCspDirectives($header));
     }
 
+    #[PreserveGlobalState(false)]
+    #[RunInSeparateProcess]
+    public function testSandboxEmptyFlagThenFlags(): void
+    {
+        $this->csp->reportOnly(false);
+        $this->csp->addSandbox('');
+        $this->csp->addSandbox('allow-scripts');
+        $this->assertTrue($this->work());
+
+        $header = $this->getHeaderEmitted('Content-Security-Policy');
+        $this->assertIsString($header);
+        $this->assertContains('sandbox allow-scripts', $this->getCspDirectives($header));
+    }
+
+    #[PreserveGlobalState(false)]
+    #[RunInSeparateProcess]
+    public function testAddOptionWithSpaceSeparatedString(): void
+    {
+        $config          = new CSPConfig();
+        $config->baseURI = 'self example.com';
+
+        $csp = new ContentSecurityPolicy($config);
+
+        $response = new Response(config(App::class));
+        $response->pretend(true);
+
+        $csp->addBaseURI('another.com');
+        $csp->finalize($response);
+
+        $directives = $this->getCspDirectives($response->getHeaderLine('Content-Security-Policy'));
+        $this->assertContains("base-uri 'self' example.com another.com", $directives);
+    }
+
+    #[PreserveGlobalState(false)]
+    #[RunInSeparateProcess]
+    public function testAddOptionWithEmptyStringTarget(): void
+    {
+        $config          = new CSPConfig();
+        $config->baseURI = '';
+
+        $csp = new ContentSecurityPolicy($config);
+
+        $response = new Response(config(App::class));
+        $response->pretend(true);
+
+        $csp->addBaseURI('example.com');
+        $csp->finalize($response);
+
+        $directives = $this->getCspDirectives($response->getHeaderLine('Content-Security-Policy'));
+        $this->assertContains('base-uri example.com', $directives);
+    }
+
+    #[PreserveGlobalState(false)]
+    #[RunInSeparateProcess]
+    public function testAddOptionNumericString(): void
+    {
+        $this->csp->addBaseURI('0');
+        $this->assertTrue($this->work());
+
+        $header = $this->getHeaderEmitted('Content-Security-Policy');
+        $this->assertIsString($header);
+        $this->assertContains('base-uri 0', $this->getCspDirectives($header));
+    }
+
     #[PreserveGlobalState(false)]
     #[RunInSeparateProcess]
     public function testUpgradeInsecureRequests(): void

user_guide_src/source/changelogs/v4.7.6.rst

@@ -31,6 +31,7 @@ Bugs Fixed
 **********
 
 - **Commands:** Fixed a bug where generator commands did not sort the imports of a template with CRLF line endings.
+- **HTTP:** Fixed a bug in ``ContentSecurityPolicy::addOption()`` where converting string directive values to array keys resulted in invalid entries for empty strings, unquoted values for space-separated lists, and ``TypeError`` for numeric strings.
 - **Security:** Fixed a bug where a valid JSON request body that is not an object
   (for example a JSON array) was corrupted after CSRF verification when the
   token was sent via the ``X-CSRF-TOKEN`` header.