CVE-2024-42472: Flatpak may allow access to files outside sandbox for certain apps

10.0 CVSS

Description

Flatpak is a Linux application sandboxing and distribution framework. Prior to versions 1.14.0 and 1.15.10, a malicious or compromised Flatpak app using persistent directories could access and write files outside of what it would otherwise have access to, which is an attack on integrity and confidentiality.

When `persistent=subdir` is used in the application permissions (represented as `--persist=subdir` in the command-line interface), that means that an application which otherwise doesn't have access to the real user home directory will see an empty home directory with a writeable subdirectory `subdir`. Behind the scenes, this directory is actually a bind mount and the data is stored in the per-application directory as `~/.var/app/$APPID/subdir`. This allows existing apps that are not aware of the per-application directory to still work as intended without general home directory access.

However, the application does have write access to the application directory `~/.var/app/$APPID` where this directory is stored. If the source directory for the `persistent`/`--persist` option is replaced by a symlink, then the next time the application is started, the bind mount will follow the symlink and mount whatever it points to into the sandbox.

Partial protection against this vulnerability can be provided by patching Flatpak using the patches in commits ceec2ffc and 98f79773. However, this leaves a race condition that could be exploited by two instances of a malicious app runnin...

Classification

CVE ID: CVE-2024-42472

CVSS Base Severity: CRITICAL

CVSS Base Score: 10.0

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

Problem Types

CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Affected Products

Vendor: flatpak

Product: flatpak

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.18% (probability of being exploited)

EPSS Percentile: 40.06% (scored less or equal to compared to others)

EPSS Date: 2025-04-18 (when was this score calculated)

Stakeholder-Specific Vulnerability Categorization (SSVC)

SSVC Exploitation: none

SSVC Technical Impact: total

SSVC Automatable: true

References

Timeline

2025-04-02 23:40:14 UTC
CVE

Flatpak may allow access to files outside sandbox for certain apps