{"id":"ALPINE-CVE-2021-21261","details":"Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. A bug was discovered in the `flatpak-portal` service that can allow sandboxed applications to execute arbitrary code on the host system (a sandbox escape). This sandbox-escape bug is present in versions from 0.11.4 and before fixed versions 1.8.5 and 1.10.0. The Flatpak portal D-Bus service (`flatpak-portal`, also known by its D-Bus service name `org.freedesktop.portal.Flatpak`) allows apps in a Flatpak sandbox to launch their own subprocesses in a new sandbox instance, either with the same security settings as the caller or with more restrictive security settings. For example, this is used in Flatpak-packaged web browsers such as Chromium to launch subprocesses that will process untrusted web content, and give those subprocesses a more restrictive sandbox than the browser itself. In vulnerable versions, the Flatpak portal 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 not in a sandbox. As a workaround, this vulnerability can be mitigated by preventing the `flatpak-portal` service from starting, but that mitigation will prevent many Flatpak apps from working correctly. This is fixed in versions 1.8.5 and 1.10.0.","modified":"2026-11-03T06:32:47.041636779Z","published":"2021-01-14T20:15:12.360Z","upstream":["CVE-2021-21261"],"references":[{"type":"ADVISORY","url":"https://security.alpinelinux.org/vuln/CVE-2021-21261"}],"affected":[{"package":{"name":"flatpak","ecosystem":"Alpine:v3.13","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.14","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.15","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.16","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.17","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.18","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.19","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.20","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.21","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.22","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.23","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}},{"package":{"name":"flatpak","ecosystem":"Alpine:v3.24","purl":"pkg:apk/alpine/flatpak?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.11.4"},{"fixed":"1.10.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2021-21261.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}