CVE-2021-213817.1HighCWE-74

CVE-2021-21381: Sandbox escape via special tokens in .desktop file

flatpak

Fixed in 1.10.2 · Affected: flatpak before 1.10.2 · Exploitation: possible (1 to 10%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

1.6%probability of exploitation in the next 30 days

75th percentile

050100

Higher than 75% of scored CVEs

7.1HighCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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 products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

flatpak · flatpak>= 0.9.4, < 1.10.2

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Possible (1 to 10%). EPSS between 1% and 10%.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Injection · Injection and Smuggling
Vendor: flatpak
Published: March 2021
Band: Possible (1 to 10%), March 2021

CoverageNo articles yet

No CyberSIXT article names CVE-2021-21381 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.