VYPR
Get started
← All advisories
High severityNVD Advisory· Published Jun 14, 2023· Updated Dec 18, 2024

Grav Server-side Template Injection via Insufficient Validation in filterFilter

CVE-2023-34252

Description

Grav is a flat-file content management system. Prior to version 1.7.42, there is a logic flaw in the GravExtension.filterFilter() function whereby validation against a denylist of unsafe functions is only performed when the argument passed to filter is a string. However, passing an array as a callable argument allows the validation check to be skipped. Consequently, a low privileged attacker with login access to Grav Admin panel and page creation/update permissions is able to inject malicious templates to obtain remote code execution. The vulnerability can be found in the GravExtension.filterFilter() function declared in /system/src/Grav/Common/Twig/Extension/GravExtension.php. Version 1.7.42 contains a patch for this issue. End users should also ensure that twig.undefined_functions and twig.undefined_filters properties in /path/to/webroot/system/config/system.yaml configuration file are set to false to disallow Twig from treating undefined filters/functions as PHP functions and executing them.

Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
getgrav/gravPackagist
< 1.7.421.7.42

Affected products

1

Patches

4
244758d43830

also handle SSTI in reduce twig filter + function

https://github.com/getgrav/gravAndy MillerJun 14, 2023via ghsa
commit
2 files changed · +29 −6
  • CHANGELOG.md+2 −1 modified
    @@ -4,10 +4,11 @@
 1. [](#new)
    * Added a new `system.languages.debug` option that adds a `<span class="translate-debug"></span>` around strings translated with `|t`. This can be styled by the theme as needed.
 1. [](#improved)
-   * More robust SSTI handling in `|filter` and `|map`
+   * More robust SSTI handling in `filter`, `map`, and `reduce` Twig filters and functions
    * Various SSTI improvements `Utils::isDangerousFunction()`
 1. [](#bugfix)
    * Fixed Twig `|map()` allowing code execution
+   * Fixed Twig `|reduce()` allowing code execution
 
 # v1.7.41.2
 ## 06/01/2023
  • system/src/Grav/Common/Twig/Extension/GravExtension.php+27 −5 modified
    @@ -171,9 +171,10 @@ public function getFilters(): array
             new TwigFilter('count', 'count'),
             new TwigFilter('array_diff', 'array_diff'),
 
-            // Security fix
-            new TwigFilter('filter', [$this, 'filterFilter'], ['needs_environment' => true]),
-            new TwigFilter('map', [$this, 'mapFilter'], ['needs_environment' => true]),
+            // Security fixes
+            new TwigFilter('filter', [$this, 'filterFunc'], ['needs_environment' => true]),
+            new TwigFilter('map', [$this, 'mapFunc'], ['needs_environment' => true]),
+            new TwigFilter('reduce', [$this, 'reduceFunc'], ['needs_environment' => true]),
         ];
     }
 
@@ -250,6 +251,11 @@ public function getFunctions(): array
             new TwigFunction('count', 'count'),
             new TwigFunction('array_diff', 'array_diff'),
             new TwigFunction('parse_url', 'parse_url'),
+
+            // Security fixes
+            new TwigFunction('filter', [$this, 'filterFunc'], ['needs_environment' => true]),
+            new TwigFunction('map', [$this, 'mapFunc'], ['needs_environment' => true]),
+            new TwigFunction('reduce', [$this, 'reduceFunc'], ['needs_environment' => true]),
         ];
     }
 
@@ -1706,7 +1712,7 @@ public function ofTypeFunc($var, $typeTest = null, $className = null)
      * @return array|CallbackFilterIterator
      * @throws RuntimeError
      */
-    function filterFilter(Environment $env, $array, $arrow)
+    function filterFunc(Environment $env, $array, $arrow)
     {
         if (!$arrow instanceof \Closure && !is_string($arrow) || Utils::isDangerousFunction($arrow)) {
             throw new RuntimeError('Twig |filter("' . $arrow . '") is not allowed.');
@@ -1722,12 +1728,28 @@ function filterFilter(Environment $env, $array, $arrow)
      * @return array|CallbackFilterIterator
      * @throws RuntimeError
      */
-    function mapFilter(Environment $env, $array, $arrow)
+    function mapFunc(Environment $env, $array, $arrow)
     {
         if (!$arrow instanceof \Closure && !is_string($arrow) || Utils::isDangerousFunction($arrow)) {
             throw new RuntimeError('Twig |map("' . $arrow . '") is not allowed.');
         }
 
         return twig_array_map($env, $array, $arrow);
     }
+
+    /**
+     * @param Environment $env
+     * @param array $array
+     * @param callable|string $arrow
+     * @return array|CallbackFilterIterator
+     * @throws RuntimeError
+     */
+    function reduceFunc(Environment $env, $array, $arrow)
+    {
+        if (!$arrow instanceof \Closure && !is_string($arrow) || Utils::isDangerousFunction($arrow)) {
+            throw new RuntimeError('Twig |reduce("' . $arrow . '") is not allowed.');
+        }
+
+        return twig_array_map($env, $array, $arrow);
+    }
 }
71bbed12f950

more SSTI fixes in Utils::isDangerousFunction()

https://github.com/getgrav/gravAndy MillerJun 13, 2023via ghsa
commit
2 files changed · +18 −1
  • CHANGELOG.md+1 −0 modified
    @@ -5,6 +5,7 @@
    * Added a new `system.languages.debug` option that adds a `<span class="translate-debug"></span>` around strings translated with `|t`. This can be styled by the theme as needed.
 1. [](#improved)
    * More robust SSTI handling in `|filter` and `|map`
+   * Various SSTI improvements `Utils::isDangerousFunction()`
 1. [](#bugfix)
    * Fixed Twig `|map()` allowing code execution
  • system/src/Grav/Common/Utils.php+17 −1 modified
    @@ -1950,7 +1950,7 @@ public static function getSupportPageTypes(array $defaults = null)
     }
 
     /**
-     * @param string|array $name
+     * @param string|array|Closure $name
      * @return bool
      */
     public static function isDangerousFunction($name): bool
@@ -2048,8 +2048,24 @@ public static function isDangerousFunction($name): bool
             'posix_setpgid',
             'posix_setsid',
             'posix_setuid',
+            'unserialize',
+            'ini_alter',
+            'simplexml_load_file',
+            'simplexml_load_string',
+            'forward_static_call',
+            'forward_static_call_array',
         ];
 
+        $name = strtolower($name);
+
+        if ($name instanceof \Closure) {
+            return false;
+        }
+
+        if (strpos($name, "\\") !== false) {
+            return false;
+        }
+
         if (is_array($name) || strpos($name, ":") !== false) {
             return false;
         }
8c2c1cb72611

better SSTI in |map and |filter

https://github.com/getgrav/gravAndy MillerJun 13, 2023via ghsa
commit
3 files changed · +11 −5
  • CHANGELOG.md+3 −1 modified
    @@ -3,8 +3,10 @@
 
 1. [](#new)
    * Added a new `system.languages.debug` option that adds a `<span class="translate-debug"></span>` around strings translated with `|t`. This can be styled by the theme as needed.
+1. [](#improved)
+   * More robust SSTI handling in `|filter` and `|map`
 1. [](#bugfix)
-   * * Fixed Twig `|map()` allowing code execution
+   * Fixed Twig `|map()` allowing code execution
 
 # v1.7.41.2
 ## 06/01/2023
  • system/src/Grav/Common/Twig/Extension/GravExtension.php+2 −2 modified
    @@ -1708,7 +1708,7 @@ public function ofTypeFunc($var, $typeTest = null, $className = null)
      */
     function filterFilter(Environment $env, $array, $arrow)
     {
-        if (is_string($arrow) && Utils::isDangerousFunction($arrow)) {
+        if (!$arrow instanceof \Closure && !is_string($arrow) || Utils::isDangerousFunction($arrow)) {
             throw new RuntimeError('Twig |filter("' . $arrow . '") is not allowed.');
         }
 
@@ -1724,7 +1724,7 @@ function filterFilter(Environment $env, $array, $arrow)
      */
     function mapFilter(Environment $env, $array, $arrow)
     {
-        if (is_string($arrow) && Utils::isDangerousFunction($arrow)) {
+        if (!$arrow instanceof \Closure && !is_string($arrow) || Utils::isDangerousFunction($arrow)) {
             throw new RuntimeError('Twig |map("' . $arrow . '") is not allowed.');
         }
  • system/src/Grav/Common/Utils.php+6 −2 modified
    @@ -1950,10 +1950,10 @@ public static function getSupportPageTypes(array $defaults = null)
     }
 
     /**
-     * @param string $name
+     * @param string|array $name
      * @return bool
      */
-    public static function isDangerousFunction(string $name): bool
+    public static function isDangerousFunction($name): bool
     {
         static $commandExecutionFunctions = [
             'exec',
@@ -2050,6 +2050,10 @@ public static function isDangerousFunction(string $name): bool
             'posix_setuid',
         ];
 
+        if (is_array($name) || strpos($name, ":") !== false) {
+            return false;
+        }
+
         if (in_array($name, $commandExecutionFunctions)) {
             return true;
         }
9d01140a63c7

Fix for dangerous tags in |map filter

https://github.com/getgrav/gravAndy MillerJun 13, 2023via ghsa
commit
2 files changed · +19 −0
  • CHANGELOG.md+2 −0 modified
    @@ -3,6 +3,8 @@
 
 1. [](#new)
    * Added a new `system.languages.debug` option that adds a `<span class="translate-debug"></span>` around strings translated with `|t`. This can be styled by the theme as needed.
+1. [](#bugfix)
+   * * Fixed Twig `|map()` allowing code execution
 
 # v1.7.41.2
 ## 06/01/2023
  • system/src/Grav/Common/Twig/Extension/GravExtension.php+17 −0 modified
    @@ -173,6 +173,7 @@ public function getFilters(): array
 
             // Security fix
             new TwigFilter('filter', [$this, 'filterFilter'], ['needs_environment' => true]),
+            new TwigFilter('map', [$this, 'mapFilter'], ['needs_environment' => true]),
         ];
     }
 
@@ -1713,4 +1714,20 @@ function filterFilter(Environment $env, $array, $arrow)
 
         return twig_array_filter($env, $array, $arrow);
     }
+
+    /**
+     * @param Environment $env
+     * @param array $array
+     * @param callable|string $arrow
+     * @return array|CallbackFilterIterator
+     * @throws RuntimeError
+     */
+    function mapFilter(Environment $env, $array, $arrow)
+    {
+        if (is_string($arrow) && Utils::isDangerousFunction($arrow)) {
+            throw new RuntimeError('Twig |map("' . $arrow . '") is not allowed.');
+        }
+
+        return twig_array_map($env, $array, $arrow);
+    }
 }

Vulnerability mechanics

Generated by null/stub on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

9

News mentions

0

No linked articles in our index yet.