### [CVE-2021-3493](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3493)
![](https://img.shields.io/static/v1?label=Product&message=linux%20kernel&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=5.8%20kernel%3C%205.8.0-50.56%20%20&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-270%3A%20Privilege%20Context%20Switching%20Error&color=brighgreen)

### 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.

### POC

#### Reference
- 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

#### Github
- https://github.com/0day404/vulnerability-poc
- https://github.com/0xMarcio/cve
- https://github.com/0xMat10/eJPT_Prep
- https://github.com/0xWhoami35/root-kernel
- https://github.com/0xsyr0/OSCP
- https://github.com/20142995/sectool
- https://github.com/ARPSyndicate/cvemon
- https://github.com/Abdennour-py/CVE-2021-3493
- https://github.com/Al1ex/LinuxEelvation
- https://github.com/AmIAHuman/OverlayFS-CVE-2021-3493
- https://github.com/Anekant-Singhai/Exploits
- https://github.com/ArrestX/--POC
- https://github.com/Awrrays/Pentest-Tips
- https://github.com/CVEDB/PoC-List
- https://github.com/CVEDB/awesome-cve-repo
- https://github.com/CVEDB/top
- https://github.com/EdgeSecurityTeam/Vulnerability
- https://github.com/GhostTroops/TOP
- https://github.com/GibzB/THM-Captured-Rooms
- https://github.com/H0j3n/EzpzCheatSheet
- https://github.com/HaxorSecInfec/autoroot.sh
- https://github.com/Ishan3011/CVE-2021-3493
- https://github.com/JERRY123S/all-poc
- https://github.com/JlSakuya/Linux-Privilege-Escalation-Exploits
- https://github.com/KayCHENvip/vulnerability-poc
- https://github.com/Metarget/metarget
- https://github.com/Miraitowa70/POC-Notes
- https://github.com/Mr-xn/Penetration_Testing_POC
- https://github.com/N1NJ10/eJPT_Prep
- https://github.com/NaInSec/CVE-PoC-in-GitHub
- https://github.com/Ostorlab/KEV
- https://github.com/Ostorlab/known_exploited_vulnerbilities_detectors
- https://github.com/ProbiusOfficial/Awsome-Sec.CTF-Videomaker
- https://github.com/SYRTI/POC_to_review
- https://github.com/SenukDias/OSCP_cheat
- https://github.com/Senz4wa/CVE-2021-3493
- https://github.com/SexyBeast233/SecBooks
- https://github.com/SirElmard/ethical_hacking
- https://github.com/SrcVme50/Analytics
- https://github.com/SrcVme50/Hospital
- https://github.com/Threekiii/Awesome-POC
- https://github.com/TrojanAZhen/Self_Back
- https://github.com/WhooAmii/POC_to_review
- https://github.com/a-roshbaik/Linux-Privilege-Escalation-Exploits
- https://github.com/abylinjohnson/linux-kernel-exploits
- https://github.com/anquanscan/sec-tools
- https://github.com/beruangsalju/LocalPrivelegeEscalation
- https://github.com/beruangsalju/LocalPrivilegeEscalation
- https://github.com/briskets/CVE-2021-3493
- https://github.com/cerodah/overlayFS-CVE-2021-3493
- https://github.com/ctrsploit/ctrsploit
- https://github.com/cyberanand1337x/bug-bounty-2022
- https://github.com/d4n-sec/d4n-sec.github.io
- https://github.com/derek-turing/CVE-2021-3493
- https://github.com/fei9747/CVE-2021-3493
- https://github.com/fei9747/LinuxEelvation
- https://github.com/hktalent/TOP
- https://github.com/hktalent/bug-bounty
- https://github.com/inspiringz/CVE-2021-3493
- https://github.com/jbmihoub/all-poc
- https://github.com/jenriquezv/OSCP-Cheat-Sheets
- https://github.com/k0mi-tg/CVE-POC
- https://github.com/kdn111/linux-kernel-exploitation
- https://github.com/kgwanjala/oscp-cheatsheet
- https://github.com/khanhdn111/linux-kernel-exploitation
- https://github.com/khanhdz-06/linux-kernel-exploitation
- https://github.com/khanhdz191/linux-kernel-exploitation
- https://github.com/khanhhdz/linux-kernel-exploitation
- https://github.com/khanhhdz06/linux-kernel-exploitation
- https://github.com/khanhnd123/linux-kernel-exploitation
- https://github.com/knd06/linux-kernel-exploitation
- https://github.com/lions2012/Penetration_Testing_POC
- https://github.com/loicoddon/TP_be_root
- https://github.com/makoto56/penetration-suite-toolkit
- https://github.com/manas3c/CVE-POC
- https://github.com/massco99/Analytics-htb-Rce
- https://github.com/migueltc13/KoTH-Tools
- https://github.com/n1njasec/information-security-modules
- https://github.com/ndk191/linux-kernel-exploitation
- https://github.com/nenandjabhata/CTFs-Journey
- https://github.com/nomi-sec/PoC-in-GitHub
- https://github.com/oneoy/CVE-2021-3493
- https://github.com/oscpname/OSCP_cheat
- https://github.com/pmihsan/OverlayFS-CVE-2021-3493
- https://github.com/ptkhai15/OverlayFS---CVE-2021-3493
- https://github.com/puckiestyle/CVE-2021-3493
- https://github.com/revanmalang/OSCP
- https://github.com/smallkill/CVE-2021-3493
- https://github.com/soosmile/POC
- https://github.com/ssr-111/linux-kernel-exploitation
- https://github.com/taielab/awesome-hacking-lists
- https://github.com/thesakibrahman/THM-Free-Room
- https://github.com/timb-machine/linux-malware
- https://github.com/trhacknon/Pocingit
- https://github.com/txuswashere/OSCP
- https://github.com/tzwlhack/Vulnerability
- https://github.com/weeka10/-hktalent-TOP
- https://github.com/whoforget/CVE-POC
- https://github.com/wkhnh06/linux-kernel-exploitation
- https://github.com/xairy/linux-kernel-exploitation
- https://github.com/xhref/OSCP
- https://github.com/xuetusummer/Penetration_Testing_POC
- https://github.com/youwizard/CVE-POC
- https://github.com/zecool/cve