GHSA-jv9c-w74q-6762

Insecure permissions on build temporary rootfs in Singularity

### Impact Insecure permissions on temporary directories used in explicit and implicit container build operations. When a Singularity command that results in a container build operation is executed, it is possible for a user with access to the system to read the contents of the image during the build. Additionally, if the image contains a world-writable file or directory, it is possible for a user to inject arbitrary content into the running build, which in certain circumstances may enable arbitrary code execution during the build and/or when the built container is run. ### Patches This issue is addressed in Singularity 3.6.3. All users are advised to upgrade to 3.6.3. ### Workarounds The issue is mitigated if `TMPDIR` is set to a location that is only accessible to the user, as any subdirectories directly under `TMPDIR` cannot then be accessed by others. However, this is difficult to enforce so it is not recommended to rely on this as a mitigation. ### For more information General questions about the impact of the advisory / changes made in the 3.6.0 release can be asked in the: * [Singularity Slack Channel](https://bit.ly/2m0g3lX) * [Singularity Mailing List](https://groups.google.com/a/lbl.gov/forum/??sdf%7Csort:date#!forum/singularity) Any sensitive security concerns should be directed to: security@sylabs.io See our Security Policy here: https://sylabs.io/security-policy