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Persist third-party plugin $_POST fields across the 2FA login screen (Fixes #705) #925

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Persist third-party plugin $_POST fields across the 2FA login screen (Fixes #705) #925

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e4d19b0
Fix #705: Persist custom fields during 2FA challenge
chetanupare Jul 6, 2026
b541118
Fix nested array vulnerabilities and wp_unslash issues with custom po…
chetanupare Jul 27, 2026
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65 changes: 65 additions & 0 deletions class-two-factor-core.php
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Original file line number Diff line number Diff line change
Expand Up @@ -1161,6 +1161,7 @@ public static function login_html( $user, $login_nonce, $redirect_to, $error_msg
<input type="hidden" name="redirect_to" value="<?php echo esc_attr( $redirect_to ); ?>" />
<?php } ?>
<input type="hidden" name="rememberme" id="rememberme" value="<?php echo esc_attr( $rememberme ); ?>" />
<?php self::print_custom_post_fields(); ?>

<?php $provider->authentication_page( $user ); ?>
</form>
Expand Down Expand Up @@ -2624,5 +2625,69 @@ public static function filter_session_information( $session, $user_id ) {

return $session;
}

/**
* Output custom $_POST fields as hidden inputs.
*
* Iterates over $_POST and outputs hidden inputs for fields added by third-party plugins,
* ensuring that standard WordPress and Two-Factor fields (especially sensitive ones like `pwd`)
* are explicitly ignored.
*
* @since 0.17.0
*/
private static function print_custom_post_fields() {
$blocklist = array(
// Standard WP Login fields.
'log',
'pwd',
'wp-submit',
'redirect_to',
'rememberme',
'interim-login',
'testcookie',
'_wpnonce',
'_wp_http_referer',
// Additional common login fields (e.g., WooCommerce, custom forms).
'password',
'user_pass',
'username',
'user_login',
// Two Factor specific fields.
'provider',
'wp-auth-id',
'wp-auth-nonce',
'action',
);

// phpcs:ignore WordPress.Security.NonceVerification.Missing
foreach ( $_POST as $key => $value ) {
if ( in_array( $key, $blocklist, true ) ) {
continue;
}
self::print_hidden_inputs( $key, wp_unslash( $value ), $blocklist );
}
}

/**
* Recursively output hidden inputs for a given key/value.
*
* @since 0.17.0
*
* @param string $name Input name.
* @param string|array $value Input value.
* @param array $blocklist Array of keys to skip.
*/
private static function print_hidden_inputs( $name, $value, $blocklist = array() ) {
if ( is_array( $value ) ) {
foreach ( $value as $k => $v ) {
if ( in_array( $k, $blocklist, true ) ) {
continue;
}
self::print_hidden_inputs( $name . '[' . $k . ']', $v, $blocklist );
}
} else {
echo '<input type="hidden" name="' . esc_attr( $name ) . '" value="' . esc_attr( $value ) . '" />' . "\n";
}
}
}

67 changes: 67 additions & 0 deletions tests/class-two-factor-core.php
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Expand Up @@ -2707,4 +2707,71 @@ public function test_add_settings_action_link() {
$this->assertStringContainsString( 'Settings', $first );
$this->assertStringContainsString( 'options-general.php', $first );
}

/**
* @covers Two_Factor_Core::print_custom_post_fields
*/
public function test_print_custom_post_fields_includes_custom_fields() {
$original_post = $_POST;
$_POST = array(
'custom_field_1' => 'value1',
'custom_array' => array(
'key1' => 'val1',
'key2' => 'val2',
),
);

$method = new ReflectionMethod( 'Two_Factor_Core', 'print_custom_post_fields' );
$method->setAccessible( true );

ob_start();
$method->invoke( null );
$output = ob_get_clean();

$_POST = $original_post;

$this->assertStringContainsString( '<input type="hidden" name="custom_field_1" value="value1" />', $output );
$this->assertStringContainsString( '<input type="hidden" name="custom_array[key1]" value="val1" />', $output );
$this->assertStringContainsString( '<input type="hidden" name="custom_array[key2]" value="val2" />', $output );
}

/**
* @covers Two_Factor_Core::print_custom_post_fields
*/
public function test_print_custom_post_fields_excludes_blocked_fields() {
$original_post = $_POST;
$_POST = array(
'pwd' => 'my_secret_password',
'password' => 'my_other_password',
'log' => 'admin',
'user_pass' => 'secret',
'rememberme' => '1',
'custom_ok' => 'allowed',
'nested' => array(
'pwd' => 'nested_secret_password',
'ok' => 'nested_allowed',
),
);

$method = new ReflectionMethod( 'Two_Factor_Core', 'print_custom_post_fields' );
$method->setAccessible( true );

ob_start();
$method->invoke( null );
$output = ob_get_clean();

$_POST = $original_post;

$this->assertStringContainsString( '<input type="hidden" name="custom_ok" value="allowed" />', $output );
$this->assertStringContainsString( '<input type="hidden" name="nested[ok]" value="nested_allowed" />', $output );
$this->assertStringNotContainsString( 'my_secret_password', $output );
$this->assertStringNotContainsString( 'my_other_password', $output );
$this->assertStringNotContainsString( 'nested_secret_password', $output );
$this->assertStringNotContainsString( 'secret', $output );
$this->assertStringNotContainsString( 'pwd', $output );
$this->assertStringNotContainsString( 'password', $output );
$this->assertStringNotContainsString( 'log', $output );
$this->assertStringNotContainsString( 'user_pass', $output );
$this->assertStringNotContainsString( 'rememberme', $output );
}
}
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