In Drupal core 8.x prior to 8.3.4 and Drupal core 7.x prior to 7.56; Private files that have been uploaded by an anonymous user but not permanently attached to content on the site should only be visible to the anonymous user that uploaded them, rather than all anonymous users. Drupal core did not previously provide this protection, allowing an access bypass vulnerability to occur. This issue is mitigated by the fact that in order to be affected, the site must allow anonymous users to upload files into a private file system.

In Drupal Core versions 7.x prior to 7.62, 8.6.x prior to 8.6.6 and 8.5.x prior to 8.5.9; Drupal core uses the third-party PEAR Archive_Tar library. This library has released a security update which impacts some Drupal configurations. Refer to CVE-2018-1000888 for details

An issue was discovered in Http Foundation in Symfony 2.7.0 through 2.7.48, 2.8.0 through 2.8.43, 3.3.0 through 3.3.17, 3.4.0 through 3.4.13, 4.0.0 through 4.0.13, and 4.1.0 through 4.1.2. It arises from support for a (legacy) IIS header that lets users override the path in the request URL via the X-Original-URL or X-Rewrite-URL HTTP request header. These headers are designed for IIS support, but it's not verified that the server is in fact running IIS, which means anybody who can send these requests to an application can trigger this. This affects \Symfony\Component\HttpFoundation\Request::prepareRequestUri() where X-Original-URL and X_REWRITE_URL are both used. The fix drops support for these methods so that they cannot be used as attack vectors such as web cache poisoning.

A remote code execution vulnerability exists within multiple subsystems of Drupal 7.x and 8.x. This potentially allows attackers to exploit multiple attack vectors on a Drupal site, which could result in the site being compromised. This vulnerability is related to Drupal core - Highly critical - Remote Code Execution - SA-CORE-2018-002. Both SA-CORE-2018-002 and this vulnerability are being exploited in the wild.

A jQuery cross site scripting vulnerability is present when making Ajax requests to untrusted domains. This vulnerability is mitigated by the fact that it requires contributed or custom modules in order to exploit. For Drupal 8, this vulnerability was already fixed in Drupal 8.4.0 in the Drupal core upgrade to jQuery 3. For Drupal 7, it is fixed in the current release (Drupal 7.57) for jQuery 1.4.4 (the version that ships with Drupal 7 core) as well as for other newer versions of jQuery that might be used on the site, for example using the jQuery Update module.

Drupal core 7.x versions before 7.57 has an external link injection vulnerability when the language switcher block is used. A similar vulnerability exists in various custom and contributed modules. This vulnerability could allow an attacker to trick users into unwillingly navigating to an external site.

Drupal 8.4.x versions before 8.4.5 and Drupal 7.x versions before 7.57 has a Drupal.checkPlain() JavaScript function which is used to escape potentially dangerous text before outputting it to HTML (as JavaScript output does not typically go through Twig autoescaping). This function does not correctly handle all methods of injecting malicious HTML, leading to a cross-site scripting vulnerability under certain circumstances. The PHP functions which Drupal provides for HTML escaping are not affected.

Drupal core 7.x versions before 7.57 when using Drupal's private file system, Drupal will check to make sure a user has access to a file before allowing the user to view or download it. This check fails under certain conditions in which one module is trying to grant access to the file and another is trying to deny it, leading to an access bypass vulnerability. This vulnerability is mitigated by the fact that it only occurs for unusual site configurations.

Open redirect vulnerability in URL-related API functions in Drupal 6.x before 6.35 and 7.x before 7.35 allows remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via vectors involving the "//" initial sequence.

Open redirect vulnerability in Drupal 6.x before 6.35 and 7.x before 7.35 allows remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via a URL in the destination parameter.