CVE-2021-3493 KEV
8.8
HIGH · CVSS 3.1 · EPSS 49.2% (pctl 99)
Patch first
On CISA KEV — known exploited in the wild, due 2022-11-10.
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.
Scoring
| CVSS | 8.8 (HIGH, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
| EPSS | 49.17% — more likely to be exploited than 99% of all CVEs |
| Weakness | CWE-270 |
| On CISA KEV | yes — remediate by 2022-11-10 |
| Public exploit | none known |
| Published | 2021-04-17 |
| Last modified | 2026-06-17 |
CISA KEV
| Name | Linux Kernel Privilege Escalation Vulnerability |
|---|---|
| Added | 2022-10-20 |
| Due | 2022-11-10 |
| Vendor / product | Linux / Kernel |
| Ransomware use | none reported |
Affected (1)
| Vendor | Product |
|---|---|
| canonical | ubuntu linux |
References
- 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
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52
- https://ubuntu.com/security/notices/USN-4917-1
- 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
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52
- https://ubuntu.com/security/notices/USN-4917-1
- https://www.openwall.com/lists/oss-security/2021/04/16/1
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-3493
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