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CVE-2021-21381
CVE ID
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CVE-2021-21381
MITRE ATT&CK
Collection
Command and Control
Credential Access
Defense Evasion
Discovery
Execution
Exfiltration
Impact
Initial Access
Lateral Movement
Persistence
Privilege Escalation
Topic Tags
Description
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
.
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CVSS V3 Severity and Metrics
General Information
Vendors
- debian,
- fedoraproject,
- flatpak
Products
- debian linux 10.0,
- fedora 33,
- fedora 34,
- flatpak
References
Advisory
Miscellaneous
Additional Info
Technical Analysis
Report as Emergent Threat Response
Report as Exploited in the Wild
CVE ID
AttackerKB requires a CVE ID in order to pull vulnerability data and references from the CVE list and the National Vulnerability Database. If available, please supply below: