CVE-2021-21261

A flaw was found in Flatpak. The Flatpak portal D-Bus service passes caller-specified environment variables to non-sandboxed processes on the host system, and in particular to the flatpak run command that is used to launch the new sandbox instance. A malicious or compromised Flatpak app could set environment variables that are trusted by the flatpak run command, and use them to execute arbitrary code that is outside the sandbox. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

This vulnerability can be mitigated by preventing the flatpak-portal service from starting. Please note that this mitigation may prevent other Flatpak apps from working correctly.