#VU50675 Race condition in firejail - CVE-2021-26910

Vulnerability identifier: #VU50675

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-26910

CWE-ID: CWE-367

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
firejail
Other software / Other software solutions

Vendor: firejail.wordpress.com

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a TOCTOU race condition between a stat operation and an OverlayFS mount operation in firejail. A local user can escalate privileges on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

firejail: 0.9.30 - 0.9.64.2

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External links
https://www.openwall.com/lists/oss-security/2021/02/09/1
https://github.com/netblue30/firejail/commit/97d8a03cad19501f017587cc4e47d8418273834b
https://github.com/netblue30/firejail/releases/tag/0.9.64.4
https://lists.debian.org/debian-lts-announce/2021/02/msg00015.html
https://unparalleled.eu/blog/2021/20210208-rigged-race-against-firejail-for-local-root/
https://unparalleled.eu/publications/2021/advisory-unpar-2021-0.txt
https://www.debian.org/security/2021/dsa-4849

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.