Unpatched extfs vulnerabilities are exploitable through suid-mode Apptainer
Summary
Unpatched extfs vulnerabilities are exploitable through suid-mode Apptainer
Original description
The description as published by the source.
Apptainer is an open source container platform for Linux. There is an ext4 use-after-free flaw that is exploitable through versions of Apptainer < 1.1.0 and installations that include apptainer-suid < 1.1.8 on older operating systems where that CVE has not been patched. That includes Red Hat Enterprise Linux 7, Debian 10 buster (unless the linux-5.10 package is installed), Ubuntu 18.04 bionic and Ubuntu 20.04 focal. Use-after-free flaws in the kernel can be used to attack the kernel for denial of service and potentially for privilege escalation.
Apptainer 1.1.8 includes a patch that by default disables mounting of extfs filesystem types in setuid-root mode, while continuing to allow mounting of extfs filesystems in non-setuid "rootless" mode using fuse2fs.
Some workarounds are possible. Either do not install apptainer-suid (for versions 1.1.0 through 1.1.7) or set allow setuid = no in apptainer.conf. This requires having unprivileged user namespaces enabled and except for apptainer 1.1.x versions will disallow mounting of sif files, extfs files, and squashfs files in addition to other, less significant impacts. (Encrypted sif files are also not supported unprivileged in apptainer 1.1.x.). Alternatively, use the limit containers options in apptainer.conf/singularity.conf to limit sif files to trusted users, groups, and/or paths, and set allow container extfs = no to disallow mounting of extfs overlay files. The latter option by itself does not disallow mounting of e…
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Ubuntu UBUNTU-CVE-2023-30549 singularity-container
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- advisory security.gentoo.org
- patch github.com
- patch github.com
- patch github.com
- web access.redhat.com
- web github.com
- web lwn.net
- web lwn.net
- web security-tracker.debian.org
- web sylabs.io
- web ubuntu.com
- web suse.com