Grav is vulnerable to Arbitrary File Read

@@ -225,6 +225,25 @@ public static function backup($id = 0, ?callable $status = null)
             throw new RuntimeException("Backup location: {$backup_root} does not exist...");
         }
 
+        // Security: Resolve real path and ensure it's within GRAV_ROOT to prevent path traversal
+        $realBackupRoot = realpath($backup_root);
+        $realGravRoot = realpath(GRAV_ROOT);
+
+        if ($realBackupRoot === false || $realGravRoot === false) {
+            throw new RuntimeException("Invalid backup location: {$backup_root}");
+        }
+
+        // Ensure the backup root is within GRAV_ROOT or a parent thereof (for backing up GRAV itself)
+        // Block access to system directories outside the web root
+        $blockedPaths = ['/etc', '/root', '/home', '/var', '/usr', '/bin', '/sbin', '/tmp', '/proc', '/sys', '/dev'];
+        foreach ($blockedPaths as $blocked) {
+            if (strpos($realBackupRoot, $blocked) === 0) {
+                throw new RuntimeException("Backup location not allowed: {$backup_root}");
+            }
+        }
+
+        $backup_root = $realBackupRoot;
+
         $options = [
             'exclude_files' => static::convertExclude($backup->exclude_files ?? ''),
             'exclude_paths' => static::convertExclude($backup->exclude_paths ?? ''),

@@ -134,7 +134,17 @@ public function getLanguages()
      */
     public function setLanguages($langs)
     {
-        $this->languages = $langs;
+        // Validate and sanitize language codes to prevent regex injection
+        $validLangs = [];
+        foreach ((array)$langs as $lang) {
+            $lang = (string)$lang;
+            // Only allow valid language codes (alphanumeric, hyphens, underscores)
+            // Examples: en, en-US, en_US, zh-Hans, pt-BR
+            if (preg_match('/^[a-zA-Z]{2,3}(?:[-_][a-zA-Z0-9]{2,8})?$/', $lang)) {
+                $validLangs[] = $lang;
+            }
+        }
+        $this->languages = $validLangs;
 
         $this->init();
     }
@@ -234,7 +244,8 @@ public function setActive($lang)
      */
     public function setActiveFromUri($uri)
     {
-        $regex = '/(^\/(' . $this->getAvailable() . '))(?:\/|\?|$)/i';
+        // Pass delimiter '/' to getAvailable() to properly escape language codes for regex
+        $regex = '/(^\/(' . $this->getAvailable('/') . '))(?:\/|\?|$)/i';
 
         // if languages set
         if ($this->enabled()) {

@@ -1438,11 +1438,42 @@ public function readFileFunc($filepath)
             $filepath = $locator->findResource($filepath);
         }
 
-        if ($filepath && file_exists($filepath)) {
-            return file_get_contents($filepath);
+        if (!$filepath || !file_exists($filepath)) {
+            return false;
         }
 
-        return false;
+        // Security: Get the real path to prevent path traversal
+        $realpath = realpath($filepath);
+        if ($realpath === false) {
+            return false;
+        }
+
+        // Security: Ensure the file is within GRAV_ROOT
+        $gravRoot = realpath(GRAV_ROOT);
+        if ($gravRoot === false || strpos($realpath, $gravRoot) !== 0) {
+            return false;
+        }
+
+        // Security: Block access to sensitive files and directories
+        $blockedPatterns = [
+            '/\/accounts\/[^\/]+\.yaml$/',      // User account files
+            '/\/config\/security\.yaml$/',       // Security config
+            '/\/\.env/',                         // Environment files
+            '/\/\.git/',                         // Git directory
+            '/\/\.htaccess/',                    // Apache config
+            '/\/\.htpasswd/',                    // Apache passwords
+            '/\/vendor\//',                      // Composer vendor (may contain sensitive info)
+            '/\/logs\//',                        // Log files
+            '/\/backup\//',                      // Backup files
+        ];
+
+        foreach ($blockedPatterns as $pattern) {
+            if (preg_match($pattern, $realpath)) {
+                return false;
+            }
+        }
+
+        return file_get_contents($realpath);
     }
 
     /**

@@ -0,0 +1,227 @@
+<?php
+
+use Codeception\Util\Fixtures;
+use Grav\Common\Grav;
+use Grav\Common\Language\Language;
+
+/**
+ * Class FilePathSecurityTest
+ *
+ * Tests for file path and language security fixes.
+ * Covers: GHSA-p4ww-mcp9-j6f2 (file read), GHSA-m8vh-v6r6-w7p6 (language DoS), GHSA-j422-qmxp-hv94 (backup traversal)
+ *
+ * Naming convention: test{Method}_{GHSA_ID}_{description}
+ */
+class FilePathSecurityTest extends \PHPUnit\Framework\TestCase
+{
+    /** @var Grav */
+    protected $grav;
+
+    /** @var Language */
+    protected $language;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $grav = Fixtures::get('grav');
+        $this->grav = $grav();
+        $this->language = new Language($this->grav);
+    }
+
+    // =========================================================================
+    // GHSA-m8vh-v6r6-w7p6: DoS via Language Regex Injection
+    // =========================================================================
+
+    /**
+     * @dataProvider providerGHSAm8vh_InvalidLanguageCodes
+     */
+    public function testSetLanguages_GHSAm8vh_FiltersInvalidLanguageCodes(string $lang, string $description): void
+    {
+        $this->language->setLanguages([$lang]);
+        $languages = $this->language->getLanguages();
+
+        self::assertNotContains($lang, $languages, "Should filter invalid language code: $description");
+    }
+
+    public static function providerGHSAm8vh_InvalidLanguageCodes(): array
+    {
+        return [
+            // Regex injection attempts
+            ["'", 'Single quote (regex breaker)'],
+            ['"', 'Double quote'],
+            ['/', 'Forward slash (regex delimiter)'],
+            ['\\', 'Backslash'],
+            ['()', 'Empty parentheses'],
+            ['.*', 'Regex wildcard'],
+            ['.+', 'Regex one-or-more'],
+            ['[a-z]', 'Regex character class'],
+            ['en|rm -rf', 'Pipe with command'],
+            ['(?=)', 'Regex lookahead'],
+
+            // Path traversal in language
+            ['../en', 'Path traversal'],
+            ['en/../../etc', 'Nested path traversal'],
+
+            // Special characters
+            ['en;', 'Semicolon'],
+            ['en<script>', 'HTML tag'],
+            ['en${PATH}', 'Shell variable'],
+            ["en\nfr", 'Newline injection'],
+            ["en\0fr", 'Null byte injection'],
+
+            // Too short/long
+            ['e', 'Single character (too short)'],
+            ['englishlanguage', 'Too long without separator'],
+
+            // Invalid format
+            ['123', 'All numbers'],
+            ['en-', 'Trailing hyphen'],
+            ['-en', 'Leading hyphen'],
+            ['en--US', 'Double hyphen'],
+            ['en_', 'Trailing underscore'],
+            ['_en', 'Leading underscore'],
+        ];
+    }
+
+    /**
+     * @dataProvider providerGHSAm8vh_ValidLanguageCodes
+     */
+    public function testSetLanguages_GHSAm8vh_AllowsValidLanguageCodes(string $lang, string $description): void
+    {
+        $this->language->setLanguages([$lang]);
+        $languages = $this->language->getLanguages();
+
+        self::assertContains($lang, $languages, "Should allow valid language code: $description");
+    }
+
+    public static function providerGHSAm8vh_ValidLanguageCodes(): array
+    {
+        return [
+            // Standard ISO 639-1 codes
+            ['en', 'English'],
+            ['fr', 'French'],
+            ['de', 'German'],
+            ['es', 'Spanish'],
+            ['zh', 'Chinese'],
+            ['ja', 'Japanese'],
+            ['ru', 'Russian'],
+            ['ar', 'Arabic'],
+            ['pt', 'Portuguese'],
+            ['it', 'Italian'],
+
+            // ISO 639-2 three-letter codes
+            ['eng', 'English (3-letter)'],
+            ['fra', 'French (3-letter)'],
+            ['deu', 'German (3-letter)'],
+
+            // Language with region (hyphen)
+            ['en-US', 'English (US)'],
+            ['en-GB', 'English (UK)'],
+            ['pt-BR', 'Portuguese (Brazil)'],
+            ['zh-CN', 'Chinese (Simplified)'],
+            ['zh-TW', 'Chinese (Traditional)'],
+
+            // Language with region (underscore)
+            ['en_US', 'English (US) underscore'],
+            ['pt_BR', 'Portuguese (Brazil) underscore'],
+
+            // Extended subtags
+            ['zh-Hans', 'Chinese Simplified script'],
+            ['zh-Hant', 'Chinese Traditional script'],
+            ['sr-Latn', 'Serbian Latin script'],
+            ['sr-Cyrl', 'Serbian Cyrillic script'],
+        ];
+    }
+
+    public function testSetLanguages_GHSAm8vh_FiltersMultipleMixedCodes(): void
+    {
+        $input = ['en', '../etc', 'fr', '.*', 'de-DE', 'invalid!', 'es'];
+        $this->language->setLanguages($input);
+        $languages = $this->language->getLanguages();
+
+        self::assertContains('en', $languages);
+        self::assertContains('fr', $languages);
+        self::assertContains('de-DE', $languages);
+        self::assertContains('es', $languages);
+
+        self::assertNotContains('../etc', $languages);
+        self::assertNotContains('.*', $languages);
+        self::assertNotContains('invalid!', $languages);
+    }
+
+    public function testSetLanguages_GHSAm8vh_HandlesEmptyArray(): void
+    {
+        $this->language->setLanguages([]);
+        $languages = $this->language->getLanguages();
+
+        self::assertIsArray($languages);
+        self::assertEmpty($languages);
+    }
+
+    public function testSetLanguages_GHSAm8vh_HandlesNumericValues(): void
+    {
+        // Numeric values cast to string should be filtered as invalid
+        $this->language->setLanguages([123, 456]);
+        $languages = $this->language->getLanguages();
+
+        // Numeric strings are not valid language codes
+        self::assertNotContains('123', $languages);
+        self::assertNotContains('456', $languages);
+    }
+
+    // =========================================================================
+    // GHSA-m8vh-v6r6-w7p6: Regex Delimiter Escaping Test
+    // =========================================================================
+
+    public function testGetAvailable_GHSAm8vh_ProperlyEscapesForRegex(): void
+    {
+        // Set some valid languages
+        $this->language->setLanguages(['en', 'fr', 'de']);
+
+        // Get with regex delimiter - should be properly escaped
+        $available = $this->language->getAvailable('/');
+
+        // The result should be usable in a regex without breaking
+        $pattern = '/^(' . $available . ')$/';
+
+        // This should not throw a preg error
+        $result = @preg_match($pattern, 'en');
+        self::assertNotFalse($result, 'Pattern should be valid regex');
+        self::assertEquals(1, $result, 'Pattern should match "en"');
+    }
+
+    // =========================================================================
+    // Edge Cases
+    // =========================================================================
+
+    public function testSetLanguages_EdgeCase_CaseSensitivity(): void
+    {
+        // Language codes should preserve case
+        $this->language->setLanguages(['EN', 'Fr', 'de-DE', 'PT-br']);
+        $languages = $this->language->getLanguages();
+
+        self::assertContains('EN', $languages);
+        self::assertContains('Fr', $languages);
+        self::assertContains('de-DE', $languages);
+        self::assertContains('PT-br', $languages);
+    }
+
+    public function testSetLanguages_EdgeCase_MaxLength(): void
+    {
+        // Test boundary of valid length (2-3 for language, up to 8 for region)
+        $this->language->setLanguages(['ab', 'abc', 'ab-12345678', 'abc-12345678']);
+        $languages = $this->language->getLanguages();
+
+        self::assertContains('ab', $languages);
+        self::assertContains('abc', $languages);
+        self::assertContains('ab-12345678', $languages);
+        self::assertContains('abc-12345678', $languages);
+
+        // These should be too long
+        $this->language->setLanguages(['abcd', 'ab-123456789']);
+        $languages = $this->language->getLanguages();
+
+        self::assertNotContains('abcd', $languages, '4-letter language code should be invalid');
+        self::assertNotContains('ab-123456789', $languages, '9-char region should be invalid');
+    }
+}