Flatpak
CVE-2021-21381
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Input neutralization, injection prevention
|
| Impact | CVSS score of 8.2 (HIGH). Attack characteristics: local attack vector, low complexity, no privileges required, user interaction required. |
| Exploit ScenarioDerived | Successful exploitation could compromise the high-severity affected system. |
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Alert meAnalysisAI
Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. Rated high severity (CVSS 8.2), this vulnerability is no authentication required, low attack complexity.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.
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Technical ContextAI · show details
This vulnerability is classified under CWE-74. Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. In Flatpack since version 0.9.4 and before version 1.10.2 has a vulnerability in the "file forwarding" feature which can be used by an attacker to gain access to files that would not ordinarily be allowed by the app's permissions. By putting the special tokens @@ and/or @@u in the Exec field of a Flatpak app's .desktop file, a malicious app publisher can trick flatpak into behaving as though the user had chosen to open a target file with their Flatpak app, which automatically makes that file available to the Flatpak app. This is fixed in version 1.10.2. A minimal solution is the first commit "Disallow @@ and @@U usage in desktop files". The follow-up commits "dir: Reserve the whole @@ prefix" and "dir: Refuse to export .desktop files with suspicious uses of @@ tokens" are recommended, but not strictly required. As a workaround, avoid installing Flatpak apps from untrusted sources, or check the contents of the exported .desktop files in exports/share/applications/*.desktop (typically ~/.local/share/flatpak/exports/share/applications/*.desktop and /var/lib/flatpak/exports/share/applications/*.desktop) to make sure that literal filenames do not follow @@ or @@u. Affected products include: Flatpak, Debian Debian Linux, Fedoraproject Fedora. Version information: version 0.9.4.
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Severity by source
AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. In Flatpack since version 0.9.4 and before version 1.10.2 has a vulnerability in the "file forwarding" feature which can be used by an attacker to gain access to files that would not ordinarily be allowed by the app's permissions. By putting the special tokens @@ and/or @@u in the Exec field of a Flatpak app's .desktop file, a malicious app publisher can trick flatpak into behaving as though the user had chosen to open a target file with their Flatpak app, which automatically makes that file available to the Flatpak app. This is fixed in version 1.10.2. A minimal solution is the first commit "Disallow @@ and @@U usage in desktop files". The follow-up commits "dir: Reserve the whole @@ prefix" and "dir: Refuse to export .desktop files with suspicious uses of @@ tokens" are recommended, but not strictly required. As a workaround, avoid installing Flatpak apps from untrusted sources, or check the contents of the exported .desktop files in exports/share/applications/*.desktop (typically ~/.local/share/flatpak/exports/share/applications/*.desktop and /var/lib/flatpak/exports/share/applications/*.desktop) to make sure that literal filenames do not follow @@ or @@u.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.
Affected Products (CPE)NVD
Sandbox escape in Flatpak versions prior to 1.16.4 allows applications to access arbitrary host filesystem paths and ach
Flatpak before 1.0.8, 1.1.x and 1.2.x before 1.2.4, and 1.3.x before 1.3.1 allows a sandbox bypass. Rated critical sever
Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. Rated high severity
In dbus-proxy/flatpak-proxy.c in Flatpak before 0.8.9, and 0.9.x and 0.10.x before 0.10.3, crafted D-Bus messages to the
Arbitrary file deletion in Flatpak versions prior to 1.16.4 allows sandboxed applications to delete files on the host sy
Message-filtering bypass in xdg-dbus-proxy before 0.1.9 lets a malicious or already-compromised sandboxed application -
Flatpak before 1.0.7, and 1.1.x and 1.2.x before 1.2.3, exposes /proc in the apply_extra script sandbox, which allows at
In Flatpak before 0.8.7, a third-party app repository could include malicious apps that contain files with inappropriate
Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. Rated high severity
Local privilege escalation to root in Flatpak before 1.18.1 lets an unprivileged user holding an active local session ab
Path traversal in Flatpak's app deployment handling of the exported files/etc directory allows a malicious Flatpak appli
Path traversal in Flatpak's handling of the export/bin directory during application deployment allows a malicious Flatpa
Exploit-DB