This release contains fixes for a high severity security issue affecting Singularity 2.3.0 through 2.5.1 on kernels that support overlay file systems (CVE-2018-12021). A malicious user with network access to the host system (e.g. ssh) could exploit this vulnerability to access sensitive information on disk and bypass directory image restrictions like those preventing the root file system from being mounted into the container.

Singularity 2.5.2 should be installed immediately, and all previous versions of Singularity should be removed. The vulnerability addressed in this release affects kernels that support overlayfs. If you are unable to upgrade immediately, you should set enable overlay = no in singularity.conf.

In addition, this release contains a large number of bug fixes. Details follow:

  • Removed the option to use overlay images with singularity mount. This flaw could allow a malicious user accessing the host system to access sensitive information when coupled with persistent ext3 overlay.
  • Fixed a race condition that might allow a malicious user to bypass directory image restrictions, like mounting the host root filesystem as a container image

Bug fixes

  • Fix an error in malloc allocation #1620
  • Honor debug flag when pulling from docker hub #1556
  • Fix a bug with passwd abort #1580
  • Allow user to override singularity.conf “mount home = no” with –home option #1496
  • Improve debugging output #1535
  • Fix some bugs in bind mounting #1525
  • Define PR_(S|G)ET_NO_NEW_PRIVS in user space so that these features will work with kernels that implement them (like Cray systems) #1506
  • Create /dev/fd and standard streams symlinks in /dev when using minimal dev mount or when specifying -c/-C/–contain option #1420
  • Fixed * expansion during app runscript creation #1486

For the full release announcement and downloads, please see the release on GitHub.