CVE-2021-3493

8.8HIGH

Key Information:

Vendor: Ubuntu
Status: Linux Kernel
Vendor: CVE Published:; 15 April 2021

Badges

👾 Exploit Exists🟡 Public PoC🦅 CISA Reported

Summary

The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.

CISA Reported

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 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.

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