CVE-2020-5291 Privilege escalation in setuid mode via user namespaces in Bubblewrap
Attackers can gain root privileges in Bubblewrap when setuid mode and unprivileged user namespaces are enabled.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2020-5291?
CVE-2020-5291 is a high-severity vulnerability in Debian Debian Linux, published on 31 Mar 2020. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Bubblewrap (bwrap) before version 0.4.1, if installed in setuid mode and the kernel supports unprivileged user namespaces, then the `bwrap --userns2` option can be used to make the setuid process keep running as root while being traceable. This can in turn be used to gain root permissions. Note that this only affects the combination of bubblewrap in setuid mode (which is typically used when unprivileged user namespaces are not supported) and the support of unprivileged user namespaces. Known to be affected are: * Debian testing/unstable, if unprivileged user namespaces enabled (not default) * Debian buster-backports, if unprivileged user namespaces enabled (not default) * Arch if using `linux-hardened`, if unprivileged user namespaces enabled (not default) * Centos 7 flatpak COPR, if unprivileged user namespaces enabled (not default) This has been fixed in the 0.4.1 release, and all affected users should update.
Which versions are affected by CVE-2020-5291?
It affects 4 products.
Products include Archlinux Arch Linux, Centos Centos, Debian Debian Linux, Projectatomic Bubblewrap.
How do I fix CVE-2020-5291?
Upgrade to a fixed version.
Is CVE-2020-5291 being exploited?
There is no known exploitation of CVE-2020-5291 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2020-5291, DEBIAN-CVE-2020-5291, GHSA-j2qp-rvxj-43vj, UBUNTU-CVE-2020-5291.