DescriptionThe do_umount function in fs/namespace.c in the Linux kernel through 3.17 does not require the CAP_SYS_ADMIN capability for do_remount_sb calls that change the root filesystem to read-only, which allows local users to cause a denial of service (loss of writability) by making certain unshare system calls, clearing the / MNT_LOCKED flag, and making an MNT_FORCE umount system call.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium (attack range: local)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)wheezy3.2.78-1fixed
wheezy (security)3.2.96-3fixed
jessie (security)3.16.51-3+deb8u1fixed
stretch (security), stretch4.9.82-1+deb9u3fixed
buster, sid4.15.4-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcewheezy(not affected)
linux-2.6sourcesqueeze(not affected)


[wheezy] - linux <not-affected> (User namespaces only usable in later kernels)
[squeeze] - linux-2.6 <not-affected> (User namespaces only usable in later kernels)
Upstream commit: (v3.18-rc1)

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