CVE-2021-3493
Linux Kernel Privilege Escalation Vulnerability - [Actively Exploited]
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.
INFO
Published Date :
April 17, 2021, 5:15 a.m.
Last Modified :
Feb. 19, 2025, 7:47 p.m.
Source :
[email protected]
Remotely Exploitable :
No
Impact Score :
6.0
Exploitability Score :
2.0
CISA KEV (Known Exploited Vulnerabilities)
For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.
The overlayfs stacking file system in Linux kernel does not properly validate the application of file capabilities against user namespaces, which could lead to privilege escalation.
Apply updates per vendor instructions.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52; https://nvd.nist.gov/vuln/detail/CVE-2021-3493
Public PoC/Exploit Available at Github
CVE-2021-3493 has a 112 public PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
Affected Products
The following products are affected by CVE-2021-3493
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2021-3493.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2021-3493 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-3493 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Modified Analysis by [email protected]
Feb. 19, 2025
Action Type Old Value New Value -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Nov. 21, 2024
Action Type Old Value New Value Added Reference http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html Added Reference http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html Added Reference http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html Added Reference https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52 Added Reference https://ubuntu.com/security/notices/USN-4917-1 Added Reference https://www.openwall.com/lists/oss-security/2021/04/16/1 -
CVE Modified by [email protected]
May. 14, 2024
Action Type Old Value New Value -
Reanalysis by [email protected]
Jul. 07, 2023
Action Type Old Value New Value Removed CWE NIST CWE-269 Added CWE NIST CWE-863 -
Reanalysis by [email protected]
Oct. 27, 2022
Action Type Old Value New Value -
Modified Analysis by [email protected]
Dec. 16, 2021
Action Type Old Value New Value Changed Reference Type http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html No Types Assigned http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html Exploit, Third Party Advisory, VDB Entry Changed Reference Type http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html No Types Assigned http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html Third Party Advisory, VDB Entry Changed Reference Type http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html No Types Assigned http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html Exploit, Third Party Advisory, VDB Entry -
CVE Modified by [email protected]
Dec. 03, 2021
Action Type Old Value New Value Added Reference http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html [No Types Assigned] -
CVE Modified by [email protected]
May. 31, 2021
Action Type Old Value New Value Added Reference http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html [No Types Assigned] -
CVE Modified by [email protected]
May. 03, 2021
Action Type Old Value New Value Added Reference http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html [No Types Assigned] -
Initial Analysis by [email protected]
Apr. 22, 2021
Action Type Old Value New Value Added CVSS V2 NIST (AV:L/AC:L/Au:N/C:C/I:C/A:C) Added CVSS V3.1 NIST AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Changed Reference Type https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52 No Types Assigned https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52 Mailing List, Patch, Third Party Advisory Changed Reference Type https://ubuntu.com/security/notices/USN-4917-1 No Types Assigned https://ubuntu.com/security/notices/USN-4917-1 Vendor Advisory Changed Reference Type https://www.openwall.com/lists/oss-security/2021/04/16/1 No Types Assigned https://www.openwall.com/lists/oss-security/2021/04/16/1 Mailing List, Third Party Advisory Added CWE NIST CWE-269 Added CPE Configuration OR *cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:lts:*:*:* versions up to (excluding) 18.04 *cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:lts:*:*:* versions from (including) 18.04.1 up to (excluding) 20.04 Added CPE Configuration OR *cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:-:*:*:* versions up to (excluding) 20.10
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-3493 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-3493
weaknesses.
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
70.67 }} 69.50%
score
0.98597
percentile