Singularity Path Traversal

Singularity (an open source container platform) from version 3.1.1 through 3.6.3 has a vulnerability. Due to insecure handling of path traversal and the lack of path sanitization within `unsquashfs`, it is possible to overwrite/create any files on the host filesystem during the extraction with a crafted squashfs filesystem. The extraction occurs automatically for unprivileged (either installation or with `allow setuid = no`) run of Singularity when a user attempt to run an image which is a local SIF image or a single file containing a squashfs filesystem and is coming from remote sources `library://` or `shub://`. Image build is also impacted in a more serious way as it can be used by a root user, allowing an attacker to overwrite/create files leading to a system compromise, so far bootstrap methods `library`, `shub` and `localimage` are triggering the squashfs extraction. This issue is addressed in Singularity 3.6.4. All users are advised to upgrade to 3.6.4 especially if they use Singularity mainly for building image as root user. There is no solid workaround except to temporary avoid to use unprivileged mode with single file images in favor of sandbox images instead. Regarding image build, temporary avoid to build from `library` and `shub` sources and as much as possible use `--fakeroot` or a VM for that. (2020-10-14, CVE-2020-15229)

Relative Path Confusion means that your web server is configured to serve responses to ambiguous URLs. This configuration can possibly cause confusion about the correct relative path for the URL. It is also an issue of resources, such as images, styles etc., which are specified in the response using relative path, not the absolute URL.

If the web browser permits to parse "cross-content" response, the attacker may be able to fool the web browser into interpreting HTML into other content types, which can then lead to a cross site scripting attack (link do XSS).