REDHAT-BUG-2157281: Medium severity LXC LXC vulnerability
lxc-user-nic in lxc through 5.0.1 is installed setuid root, and may allow local users to infer whether any file exists, even within a protected directory tree, because "Failed to open" often indicates that a file does not exist, whereas "does not refer to a network namespace path" often indicates that a file exists. NOTE: this is different from CVE-2018-6556 because the CVE-2018-6556 fix design was based on the premise that "we will report back to the user that the open() failed but the user has no way of knowing why it failed"; however, in many realistic cases, there are no plausible reasons for failing except that the file does not exist.
https://github.com/MaherAzzouzi/CVE-2022-47952 https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1783591/comments/45 https://github.com/lxc/lxc/blob/0b83d71c2c8f3bac9503f894cd84584f79258bb3/lxc.spec.in#L274 https://github.com/lxc/lxc/blob/0b83d71c2c8f3bac9503f894cd84584f79258bb3/src/lxc/cmd/lxcusernic.c#L1085-L1104
Affected Software
Event History
Frequently Asked Questions
Who can exploit this issue?
A local user who can invoke the setuid-root lxc-user-nic utility may be able to use its differing error messages to infer whether files exist, including files under protected directory trees.
What information can an attacker obtain?
The issue exposes file-existence information rather than file contents. A “Failed to open” message can indicate that a file does not exist, while “does not refer to a network namespace path” can indicate that it exists.
Which LXC versions are affected?
The provided information states that lxc through version 5.0.1 is affected.