AEGLIX vulnerability intelligence
CVE-2021-3493
HIGH · CVSS 8.8 · Analyzed
Published: 2021-04-17 · Updated: 2026-06-17 · Source: NVD
Vulnerability overview
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.
Severity and scoring
- CVSS score
- 8.8 · HIGH
- CVSS version
- 3.1
- CVSS vector
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- Weaknesses
- CWE-270, CWE-863
CVSS measures technical severity; it does not establish whether this vulnerability is being exploited in your environment.
Known exploitation and remediation
Listed in CISA’s Known Exploited Vulnerabilities catalog.
- Affected product
- Linux · Kernel
- Added to catalog
- 2022-10-20
- Required action
- Apply updates per vendor instructions.
- CISA remediation due date
- 2022-11-10
CISA deadlines apply to the organizations covered by its directives. Confirm your own remediation requirements.
Verify affected versions and patch availability in the vendor advisory before making changes.
Affected products and versions
cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:lts:*:*:*
Before (exclusive): 18.04
cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:lts:*:*:*
From (inclusive): 18.04.1
Before (exclusive): 20.04
cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:-:*:*:*
Before (exclusive): 20.10
These are NVD CPE applicability entries. Some products depend on configuration conditions; consult the official record to confirm applicability.
Advisories and references
- http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html
Exploit · Third Party Advisory · VDB Entry
- http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html
Press/Media Coverage · Third Party Advisory · VDB Entry
- http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html
Exploit · Third Party Advisory · VDB Entry
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52
Mailing List · Patch · Third Party Advisory
- https://ubuntu.com/security/notices/USN-4917-1
Vendor Advisory
- https://www.openwall.com/lists/oss-security/2021/04/16/1
Mailing List · Third Party Advisory
- http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html
Exploit · Third Party Advisory · VDB Entry
- http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html
Press/Media Coverage · Third Party Advisory · VDB Entry
- http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html
Exploit · Third Party Advisory · VDB Entry
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52
Mailing List · Patch · Third Party Advisory
- https://ubuntu.com/security/notices/USN-4917-1
Vendor Advisory
- https://www.openwall.com/lists/oss-security/2021/04/16/1
Mailing List · Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-3493
US Government Resource