Vulnerability detail
Enriched intelligence for a single CVE
High
CVE-2021-3493
PUBLISHEDThe overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on...
- Vendor
- Ubuntu
- Product
- linux kernel
- Published
- Apr 17, 2021
- EPSS
- —
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.
CVSS scores
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Exploitation status
Exploited in the wild
Recorded 2022-10-20 00:00:00 UTC · Source
SSVC decision points
- Exploitation
- active
- Automatable
- No
- Technical impact
- total
References
- https://ubuntu.com/security/notices/USN-4917-1
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52
- https://www.openwall.com/lists/oss-security/2021/04/16/1
- http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html
- http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html
- http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html
Known exploited vulnerability sources
Catalogues that list this CVE as a known exploited vulnerability.
| Source | Added |
|---|---|
| CISA | Oct 20, 2022 |
Scanner integrations
| Scanner | Reference | Detected |
|---|---|---|
| Metasploit | https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/local/cve_2021_3493_overlayfs.rb | Apr 28, 2025 |
Potential proof of concepts
These PoCs are unverified and could contain malware. Use at your own risk.
github · Created 2024-07-04 17:29:28 UTC · 0 stars
github · Created 2021-10-02 14:44:43 UTC · 0 stars
github · Created 2021-07-07 06:16:48 UTC · 39 stars
CVE-2021-3493 Ubuntu OverlayFS Local Privesc (Interactive Bash Shell & Execute Command Entered)
github · Created 2021-04-22 02:06:21 UTC · 3 stars
github · Created 2021-04-19 20:07:01 UTC · 418 stars
Ubuntu OverlayFS Local Privesc
Timeline
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CVE ID Reserved
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CVE Published to Public
-
Added to KEVIntel
-
Detected by Metasploit