CVE-2021-3493
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.
- Published Apr 17, 2021
- CVSS 7.8 high
- 49.2% chance of exploitation in the next 30 days (EPSS)
- In CISA's Known Exploited Vulnerabilities catalog
- A Metasploit module exploits it
- A fix is available