CVE-2021-3493
KEVHIGH 7.8EPSS 49.2%
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
- Ubuntu · linux kernel
- CVSS v3.1 NVD
- 7.8 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - CVSS v3.1 UBUNTU
- 8.8 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - CVSS v2.0 NVD
- 7.2 HIGH
AV:L/AC:L/Au:N/C:C/I:C/A:C - EPSS
- 49.17% chance of exploitation in the next 30 days, 99th percentile
- CISA KEV
- added 2022-10-20
- Published
- 2021-04-17
- Updated
- 2025-10-21
Proof-of-concept exploits (21)
- http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1…
- http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.h…
- 0xWhoami35/root-kernel0★ · 2026-07-21
- Abdennour-py/CVE-2021-34930★ · 2021-05-02
- Sornphut/OverlayFS---CVE-2021-34930★ · 2025-03-05
- azazhe1/Ransomware_CVE_2021_34930★ · 2025-04-15
- briskets/CVE-2021-3493442★ · 2024-04-02
- cerodah/overlayFS-CVE-2021-34931★ · 2021-09-12
- derek-turing/CVE-2021-34930★ · 2021-07-16
- fathallah17/OverlayFS-CVE-2021-34930★ · 2024-09-16
- fei9747/CVE-2021-34931★ · 2022-11-29
- iamz24/CVE-2021-3493_CVE-2022-33570★ · 2024-07-04
- inspiringz/CVE-2021-349342★ · 2021-07-07
- oneoy/CVE-2021-34933★ · 2021-04-22
- pmihsan/OverlayFS-CVE-2021-34930★ · 2023-01-16
- ptkhai15/OverlayFS---CVE-2021-34930★ · 2023-08-25
- puckiestyle/CVE-2021-34932★ · 2021-10-02
- 0xlane/CVE-2021-34930★ · 2026-07-23
- WhatsWrongAndWhy/CVE-2021-34930★ · 2026-07-21
- cyberx-1/OverlayFS-CVE-2021-34930★ · 2025-10-22
- r3dw4n48m3d/CVE-2021-3493-Exploit0★ · 2026-09-01
Metasploit modules (1)
Exploit collections (2)
- CVE-2021-3493-Ubuntu Linux 本地提权helloexp/0day
- Ubuntu OverlayFS 权限提升漏洞（CVE-2021-3493）.mdtzwlhack/Vulnerability
Security advisories
- https://ubuntu.com/security/notices/USN-4917-1
- http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.h…
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a…
- https://www.openwall.com/lists/oss-security/2021/04/16/1