Race condition in firejail - CVE-2021-26910
Published: February 14, 2021
Vulnerability identifier: #VU50675
CSH Severity: Low
CVSS v4: 8.5 [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]
CVE-ID: CVE-2021-26910
CWE-ID: CWE-367
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
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.
Affected software
firejail
Arch Linux
Gentoo Linux
Ubuntu
firejail (Debian package)
firejail (Ubuntu package)
Arch Linux
Gentoo Linux
Ubuntu
firejail (Debian package)
firejail (Ubuntu package)
How to mitigate CVE-2021-26910
Install updates from vendor's website.
firejail - update to 0.9.64.4
firejail (Debian package) - update to 0.9.58.2-2+deb10u2
firejail (Ubuntu package) - update to 0.9.62-3ubuntu0.1
firejail (Debian package) - update to 0.9.58.2-2+deb10u2
firejail (Ubuntu package) - update to 0.9.62-3ubuntu0.1
External References
- http://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