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CVE-2021-3493

Quick assessment

Affected
Ubuntu linux kernel
Exploitation
Confirmed exploitation in the wild; remediate immediately
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 linux kernel 存在安全漏洞，该漏洞源于非特权用户名称空间和Ubuntu内核中允许非特权覆盖的补丁的组合，攻击者可利用该漏洞可以使用它来获得更高的特权。

CVSS 8.8 · High KEV EPSS 49.17% · P99

Public Exploits 1

Metasploit · 1 cve_2021_3493_overlayfs.rb [exploit]

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation
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I. Basic Information for CVE-2021-3493

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
特权上下文切换错误
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 linux kernel 存在安全漏洞，该漏洞源于非特权用户名称空间和Ubuntu内核中允许非特权覆盖的补丁的组合，攻击者可利用该漏洞可以使用它来获得更高的特权。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Shenlong Deep Dive — AI Deep Analysis

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Affected Products

Vendor Product Affected Versions CPE Subscribe
Ubuntu linux kernel 5.8 kernel ~ 5.8.0-50.56 -

II. Public POCs for CVE-2021-3493

# POC Description Source Link Shenlong Link
1 Ubuntu OverlayFS Local Privesc https://github.com/briskets/CVE-2021-3493 POC Details
2 None https://github.com/oneoy/CVE-2021-3493 POC Details
3 None https://github.com/Abdennour-py/CVE-2021-3493 POC Details
4 None https://github.com/Ishan3011/CVE-2021-3493 POC Details
5 CVE-2021-3493 Ubuntu OverlayFS Local Privesc (Interactive Bash Shell & Execute Command Entered) https://github.com/inspiringz/CVE-2021-3493 POC Details
6 CVE-2021-3493 Ubuntu漏洞 https://github.com/derek-turing/CVE-2021-3493 POC Details
7 2021 kernel vulnerability in Ubuntu. https://github.com/cerodah/overlayFS-CVE-2021-3493 POC Details
8 None https://github.com/puckiestyle/CVE-2021-3493 POC Details
9 None https://github.com/Senz4wa/CVE-2021-3493 POC Details
10 None https://github.com/fei9747/CVE-2021-3493 POC Details
11 Exploit For OverlayFS https://github.com/pmihsan/OverlayFS-CVE-2021-3493 POC Details
12 None https://github.com/smallkill/CVE-2021-3493 POC Details
13 None https://github.com/ptkhai15/OverlayFS---CVE-2021-3493 POC Details
14 None https://github.com/fathallah17/OverlayFS---CVE-2021-3493 POC Details
15 Exploit a 2021 Kernel vulnerability in Ubuntu to become root almost instantly! https://github.com/fathallah17/OverlayFS-CVE-2021-3493 POC Details
16 None https://github.com/Sornphut/OverlayFS---CVE-2021-3493 POC Details
17 None https://github.com/Threekiii/Awesome-POC/blob/master/%E6%93%8D%E4%BD%9C%E7%B3%BB%E7%BB%9F%E6%BC%8F%E6%B4%9E/Linux%20kernel%20%E6%9D%83%E9%99%90%E6%8F%90%E5%8D%87%E6%BC%8F%E6%B4%9E%20CVE-2021-3493.md POC Details
18 A penetration test of Ubuntu Touch 16.04 that identified 7 vulnerabilities, including a critical kernel exploit (CVE-2021-3493) allowing root access. This report provides findings and actionable hardening recommendations. https://github.com/spideyctf/UbuntuTouchSecurityVAPTReport POC Details
19 root Privileges https://github.com/cyberx-1/OverlayFS-CVE-2021-3493 POC Details
20 CVE-2021-3493 OverlayFS privilege escalation exploit framework with advanced red team features. Includes persistence mechanisms, post-exploitation modules, stealth capabilities, and comprehensive documentation. For authorized testing only. https://github.com/George-Yanni/DeepRoot POC Details
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III. Intelligence Information for CVE-2021-3493

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Patches & Fixes for CVE-2021-3493 (1)

Vendor Advisories for CVE-2021-3493 (1)

Exploits & Public PoCs for CVE-2021-3493 (3)

Mailing List Discussions for CVE-2021-3493 (1)

IV. Related Vulnerabilities

Same product: linux kernel
Same vendor: Ubuntu
Same weakness: CWE-270

V. Comments for CVE-2021-3493

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