Bug 1888811 (CVE-2020-15229) - CVE-2020-15229 singularity: path traversal and files overwrite with unsquashfs
Summary: CVE-2020-15229 singularity: path traversal and files overwrite with unsquashfs
Status: CLOSED DUPLICATE of bug 1887917
Alias: CVE-2020-15229
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1887917 1888812 1888813
TreeView+ depends on / blocked
Reported: 2020-10-15 18:56 UTC by Guilherme de Almeida Suckevicz
Modified: 2020-10-15 19:11 UTC (History)
3 users (show)

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Last Closed: 2020-10-15 19:11:59 UTC

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Description Guilherme de Almeida Suckevicz 2020-10-15 18:56:32 UTC
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.


Upstream patches:

Comment 1 Guilherme de Almeida Suckevicz 2020-10-15 18:56:50 UTC
Created singularity tracking bugs for this issue:

Affects: epel-all [bug 1888813]
Affects: fedora-all [bug 1888812]

Comment 2 Dave Dykstra 2020-10-15 19:11:59 UTC

*** This bug has been marked as a duplicate of bug 1887917 ***

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