CVE-2020-5291

Privilege escalation in setuid mode via user namespaces in Bubblewrap

HIGH
7.8
CVSS Score
Published: March 31, 2020 at 06:00 PM UTC
Updated: June 17, 2026 at 03:21 AM UTC
5 products affected across 5 vendorsDebian LinuxCentosArchlinux

Using bubblewrap by containers?

Get instant alerts when new vulnerabilities affect bubblewrap - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
HIGH7.8
Exploit prediction
EPSS 0.9%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

All versions
v < 0.4.1
Affected range stops below 0.4.1, so it looks safe — our inference, not a vendor statement
v < 0.4.1
Affected range stops below 0.4.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-648CWE-269

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card