Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date: Tue, 12 Aug 2014 14:48:28 -0700
From: Kenton Varda <>
Subject: CVE Request: ro bind mount bypass using user namespaces

Due to a bug in the Linux kernel's implementation of remount, on systems
with unprivileged user namespaces enabled, it is possible for an
unprivileged user to gain write access to any visible read-only bind mount.
It is also possible to bypass flags like nodev, nosuid, and noexec.

This problem affects sandboxing / containerization systems that do not
expose the regular filesystem to the sandboxed process, but do expose a
bind-mounted view of that filesystem using these flags to enforce security.
This bug may enable a sandbox break-out. Sandboxes which have used
seccomp-bpf to disable the "mount" system call or to disable user
namespaces are likely safe.

Eric Biederman has proposed the following patches to fix the problem:

-Kenton Varda,

Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.