[ASA-202105-17] runc: sandbox escape

[Jonas Witschel]

Arch Linux Security Advisory ASA-202105-17
==========================================

Severity: High
Date    : 2021-05-25
CVE-ID  : CVE-2021-30465
Package : runc
Type    : sandbox escape
Remote  : No
Link    : https://security.archlinux.org/AVG-1972

Summary
=======

The package runc before version 1.0.0rc95-1 is vulnerable to sandbox
escape.

Resolution
==========

Upgrade to 1.0.0rc95-1.

# pacman -Syu "runc>=1.0.0rc95-1"

The problem has been fixed upstream in version 1.0.0rc95.

Workaround
==========

Container hardening mechanisms such as LSMs (AppArmor/SELinux) and user
namespaces can restrict the amount of damage an attacker could do but
they do not block this attack outright.

Description
===========

runc 1.0.0-rc94 and earlier are vulnerable to a symlink exchange attack
where an attacker with the ability to start containers using a custom
volume configuration can request a seemingly-innocuous container
configuration that results in the host filesystem being bind-mounted
into the container (allowing for a container escape).

Impact
======

An attacker can escape from a container and access arbitrary files on
the host system using a crafted container configuration.

References
==========

https://github.com/opencontainers/runc/security/advisories/GHSA-c3xm-pvg7-gh7r
https://github.com/opencontainers/runc/commit/0ca91f44f1664da834bc61115a849b56d22f595f
https://security.archlinux.org/CVE-2021-30465
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