CVE-2021-21261
7.3 · HIGHOverview
CVE-2021-21261 is a high-severity vulnerability affecting flatpak flatpak. It was published on January 14, 2021 and has a CVSS 3.1 base score of 7.3 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.3, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
Technical Description
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-san
Remediation
Check the references section for vendor advisories and patches from flatpak. Update flatpak to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| flatpak | flatpak | >= 0.11.4, < 1.8.5 | Affected |
References
Frequently Asked Questions
What is CVE-2021-21261?
CVE-2021-21261 is a high-severity vulnerability affecting flatpak flatpak. It was published on January 14, 2021 and has a CVSS 3.1 base score of 7.3 (HIGH).
How severe is CVE-2021-21261?
This vulnerability has a CVSS 3.1 base score of 7.3, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2021-21261?
Check the references section for vendor advisories and patches from flatpak. Update flatpak to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-21261?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-21261 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
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Browser-based exploitation validates findings with real proof-of-concept.
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