Local Privilege Escalation in Linux Kernel OverlayFS Implementation - Ubuntu
CVE-2021-3493
Key Information:
Badges
What is CVE-2021-3493?
The OverlayFS implementation in the Linux kernel failed to adequately validate user namespaces when setting file capabilities on underlying file systems. This weakness, combined with specific patches in the Ubuntu kernel that permit unprivileged overlay mounts, enables attackers to exploit the situation and potentially gain elevated privileges. Users operating on affected versions should consider applying relevant security updates immediately.
CISA has reported CVE-2021-3493
CISA provides regional cyber and physical services to support security and resilience across the United States. CISA monitor the most dangerious vulnerabilities and have identifed CVE-2021-3493 as being exploited but is not known by the CISA to be used in ransomware campaigns. This is subject to change at pace
The CISA's recommendation is: Apply updates per vendor instructions.
Affected Version(s)
linux kernel 5.8 kernel < 5.8.0-50.56
linux kernel 5.4 kernel < 5.4.0-72.80
linux kernel 4.15 kernel < 4.15.0-142.146
Exploit Proof of Concept (PoC)
PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.
References
EPSS Score
72% chance of being exploited in the next 30 days.
CVSS V3.1
Timeline
- 🟡
Public PoC available
- 👾
Exploit known to exist
- 🦅
CISA Reported
Vulnerability published
Vulnerability Reserved