CVE-2021-3493
Linux Kernel Privilege Escalation Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
Required action
Apply updates per vendor instructions.
CISA notes
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52; https://nvd.nist.gov/vuln/detail/CVE-2021-3493
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.
Severity
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HAffected Products
| Vendor | Product | Affected versions |
|---|---|---|
| Ubuntu | linux kernel | 5.8 kernel to <5.8.0-50.56 5.4 kernel to <5.4.0-72.80 4.15 kernel to <4.15.0-142.146 4.4 kernel to <4.4.0-209.241 |
References
6 Links- 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
Record Details
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