#VU17726 Privilege escalation in Flatpak - CVE-2019-8308

Vulnerability identifier: #VU17726

Vulnerability risk: Low

CVSSv4.0: 7 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/U:Clear]

CVE-ID: CVE-2019-8308

CWE-ID: CWE-264

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
Flatpak
Server applications / Frameworks for developing and running applications

Vendor: Flatpak

Description

The vulnerability allows an adjacent attacker to escalate privileges on the system.

The vulnerability exists due an error when handling file descriptors related to /proc/self/exe. An adjacent attacker can trick the victim with root privileges into installing a system-wide Flatpak application that has an apply_extra script, and then run the apply_extra script in a sandbox with /proc mounted to escape sandbox protections and maliciously modify executable files as root on the host system.

Mitigation
The vulnerability has been addressed in the versions 1.0.7, 1.2.3.

Vulnerable software versions

Flatpak: 1.0.0 - 1.0.6, 1.1.0 - 1.1.3, 1.2.0 - 1.2.2

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External links
https://github.com/flatpak/flatpak/commit/cd2142888fc4c199723a0dfca1f15ea8788a5483
https://github.com/flatpak/flatpak/releases/tag/1.0.7
https://github.com/flatpak/flatpak/releases/tag/1.2.3

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.