8.8
High
CVE-2021-3493 Linux Kernel Privilege Escalation Vulnerability
Active exploitation observed
· CISA KEV catalogue
Required action
Apply updates per vendor instructions.
Ransomware campaigns
Not observed so far
Weakness
CWE-862
Description
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.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| Linux kernel 5.8 | earliest → < 5.8.0-50.56 | 5.8.0-50.56 |
| Linux kernel 5.4 | earliest → < 5.4.0-72.80 | 5.4.0-72.80 |
| Linux kernel 4.15 | earliest → < 4.15.0-142.146 | 4.15.0-142.146 |
| Linux kernel 4.4 | earliest → < 4.4.0-209.241 | 4.4.0-209.241 |