diff --git a/src/Controller/SystemConfigurationController.php b/src/Controller/SystemConfigurationController.php
index 729414bc..36a1e355 100644
--- a/src/Controller/SystemConfigurationController.php
+++ b/src/Controller/SystemConfigurationController.php
@@ -23,6 +23,7 @@ use App\Form\Type\TrackingModeType;
 use App\Form\Type\WeekDaysType;
 use App\Form\Type\YesNoType;
 use App\Repository\ConfigurationRepository;
+use App\Validator\Constraints\AllowedHtmlTags;
 use App\Validator\Constraints\DateTimeFormat;
 use App\Validator\Constraints\TimeFormat;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Security;
@@ -438,12 +439,14 @@ final class SystemConfigurationController extends AbstractController
                         ->setName('theme.branding.company')
                         ->setTranslationDomain('system-configuration')
                         ->setRequired(false)
-                        ->setType(TextType::class),
+                        ->setType(TextType::class)
+                        ->setConstraints([new AllowedHtmlTags(['tags' => '<b><i><u><strong><em><img><svg>'])]),
                     (new Configuration())
                         ->setName('theme.branding.mini')
                         ->setTranslationDomain('system-configuration')
                         ->setRequired(false)
-                        ->setType(TextType::class),
+                        ->setType(TextType::class)
+                        ->setConstraints([new AllowedHtmlTags(['tags' => '<b><i><u><strong><em><img><svg>'])]),
                     (new Configuration())
                         ->setName('theme.branding.title')
                         ->setTranslationDomain('system-configuration')
diff --git a/src/Validator/Constraints/AllowedHtmlTags.php b/src/Validator/Constraints/AllowedHtmlTags.php
new file mode 100644
index 00000000..5ac32eb0
--- /dev/null
+++ b/src/Validator/Constraints/AllowedHtmlTags.php
@@ -0,0 +1,45 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Validator\Constraints;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * @Annotation
+ * @Target({"PROPERTY", "METHOD", "ANNOTATION"})
+ */
+class AllowedHtmlTags extends Constraint
+{
+    public const DISALLOWED_TAGS_FOUND = 'kimai-allowed-html-tags-00';
+
+    public $tags;
+
+    protected static $errorNames = [
+        self::DISALLOWED_TAGS_FOUND => 'The given value contains disallowed HTML tags.',
+    ];
+
+    public $message = 'This string contains invalid HTML tags.';
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getDefaultOption()
+    {
+        return 'tags';
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getRequiredOptions()
+    {
+        return ['tags'];
+    }
+}
diff --git a/src/Validator/Constraints/AllowedHtmlTagsValidator.php b/src/Validator/Constraints/AllowedHtmlTagsValidator.php
new file mode 100644
index 00000000..353fcb8c
--- /dev/null
+++ b/src/Validator/Constraints/AllowedHtmlTagsValidator.php
@@ -0,0 +1,47 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Validator\Constraints;
+
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+use Symfony\Component\Validator\Exception\UnexpectedValueException;
+
+class AllowedHtmlTagsValidator extends ConstraintValidator
+{
+    /**
+     * @param string|mixed $value
+     * @param Constraint $constraint
+     */
+    public function validate($value, Constraint $constraint)
+    {
+        if (!($constraint instanceof AllowedHtmlTags)) {
+            throw new UnexpectedTypeException($constraint, __NAMESPACE__ . '\AllowedHtmlTags');
+        }
+
+        if (null === $value || '' === $value) {
+            return;
+        }
+
+        if (!is_scalar($value) && !(\is_object($value) && method_exists($value, '__toString'))) {
+            throw new UnexpectedValueException($value, 'string');
+        }
+
+        $value = (string) $value;
+
+        if (strip_tags($value, $constraint->tags) !== $value) {
+            $this->context->buildViolation('This string contains invalid HTML tags.')
+                ->setTranslationDomain('validators')
+                ->setParameter('{{ value }}', $this->formatValue($value))
+                ->setCode(AllowedHtmlTags::DISALLOWED_TAGS_FOUND)
+                ->addViolation();
+        }
+    }
+}
diff --git a/templates/base.html.twig b/templates/base.html.twig
index e491ff95..897e15e5 100644
--- a/templates/base.html.twig
+++ b/templates/base.html.twig
@@ -72,7 +72,7 @@
 
 {% block logo_mini %}
     {% if not kimai_context.branding.mini is empty %}
-        {{ kimai_context.branding.mini|striptags('<b><i><u><strong><em>')|raw }}
+        {{ kimai_context.branding.mini|raw }}
     {% else %}
         <b>K</b>TT
     {% endif %}
@@ -80,7 +80,7 @@
 
 {% block logo_large %}
     {% if not kimai_context.branding.company is empty %}
-        {{ kimai_context.branding.company|striptags('<b><i><u><strong><em>')|raw }}
+        {{ kimai_context.branding.company|raw }}
     {% else %}
         <b>Kimai</b> - Time Tracking
     {% endif %}
diff --git a/tests/Validator/Constraints/AllowedHtmlTagsTest.php b/tests/Validator/Constraints/AllowedHtmlTagsTest.php
new file mode 100644
index 00000000..894d9646
--- /dev/null
+++ b/tests/Validator/Constraints/AllowedHtmlTagsTest.php
@@ -0,0 +1,101 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Tests\Validator\Constraints;
+
+use App\Validator\Constraints\AllowedHtmlTags;
+use App\Validator\Constraints\AllowedHtmlTagsValidator;
+use Symfony\Component\Validator\Constraints\NotBlank;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+use Symfony\Component\Validator\Test\ConstraintValidatorTestCase;
+
+/**
+ * @covers \App\Validator\Constraints\AllowedHtmlTags
+ * @covers \App\Validator\Constraints\AllowedHtmlTagsValidator
+ */
+class AllowedHtmlTagsTest extends ConstraintValidatorTestCase
+{
+    protected function createValidator()
+    {
+        return new AllowedHtmlTagsValidator();
+    }
+
+    public function testConstraintIsInvalid()
+    {
+        $this->expectException(UnexpectedTypeException::class);
+
+        $this->validator->validate('foo', new NotBlank());
+    }
+
+    public function testConstraintIsInvalidObject()
+    {
+        $this->expectException(UnexpectedTypeException::class);
+
+        $constraint = new AllowedHtmlTags(['tags' => '']);
+        $this->validator->validate(new \stdClass(), $constraint);
+    }
+
+    /**
+     * @dataProvider getValidValues
+     * @param string $allowedTags
+     * @param string $testString
+     */
+    public function testConstraintWithValidValue(string $allowedTags, string $testString)
+    {
+        $constraint = new AllowedHtmlTags(['tags' => $allowedTags]);
+        $this->validator->validate($testString, $constraint);
+        $this->assertNoViolation();
+    }
+
+    public function testNullIsInvalid()
+    {
+        $this->validator->validate(null, new AllowedHtmlTags(['tags' => '<i>', 'message' => 'myMessage']));
+
+        $this->assertNoViolation();
+    }
+
+    public function getValidValues()
+    {
+        return [
+            ['', 'foo'],
+            ['', ''],
+            ['<i>', 'foo<i>kjhg</i>'],
+            ['<i>', 'foo<I>kjhg</I>'],
+            ['<u><i>', 'foo<i>kj<u>h</u>g</i><u>kjhgk</u>'],
+        ];
+    }
+
+    public function getInvalidValues()
+    {
+        return [
+            ['', 'foo<i>kjhg</i>'],
+            ['<u>', 'foo<i>kjhg</i>'],
+            ['<i>', 'foo<u>kjhg</u>'],
+        ];
+    }
+
+    /**
+     * @dataProvider getInvalidValues
+     * @param string $allowedTags
+     * @param string $testString
+     */
+    public function testValidationError(string $allowedTags, string $testString)
+    {
+        $constraint = new AllowedHtmlTags([
+            'tags' => $allowedTags,
+        ]);
+
+        $this->validator->validate($testString, $constraint);
+
+        $this->buildViolation('This string contains invalid HTML tags.')
+            ->setParameter('{{ value }}', '"' . $testString . '"')
+            ->setCode(AllowedHtmlTags::DISALLOWED_TAGS_FOUND)
+            ->assertRaised();
+    }
+}