CVE-2021-3493
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I. Basic Information for CVE-2021-3493
Vulnerability Information
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Vulnerability Title
N/A
Source: NVD (National Vulnerability Database)
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: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source: NVD (National Vulnerability Database)
Vulnerability Type
特权上下文切换错误
Source: NVD (National Vulnerability Database)
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
10-question deep dive: root cause, exploitation, mitigation, urgency. Read summary free, full version requires login.
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 |
AI-Generated POCPremium
No public POC found.
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- https://ubuntu.com/security/notices/USN-4917-1x_refsource_MISC
- https://www.openwall.com/lists/oss-security/2021/04/16/1x_refsource_MISC
- https://nvd.nist.gov/vuln/detail/CVE-2021-3493
IV. Related Vulnerabilities
Same product: linux kernel
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Race condition vulnerability in Linux kernel bluetooth sniff - CVE-2024-24860
Race condition vulnerability in Linux kernel bluetooth drive
Same weakness: CWE-270
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Windows Administrator Protection Elevation of Privilege Vuln - CVE-2025-9408
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V. Comments for CVE-2021-3493
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