CVE-2021-3492: (Pwn2Own) Canonical Ubuntu ShiftFS File System Double Free Privilege Escalation Vulnerability
First published: Sat Apr 17 2021(Updated: )
Last updated 11 April 2025
Credit: security@ubuntu.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Ubuntu | <18.04 | |
| Ubuntu | >=18.04.1<20.04 | |
| Ubuntu | <20.10 | |
| Ubuntu Unattended Upgrades | ||
| debian/linux | 5.10.223-1 5.10.234-1 6.1.129-1 6.1.133-1 6.12.21-1 6.12.22-1 |
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Reference Links
- http://packetstormsecurity.com/files/162614/Kernel-Live-Patch-Security-Notice-LSN-0077-1.html
- https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=25c891a949bf918b59cbc6e4932015ba4c35c333
- https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=8fee52ab9da87d82bc6de9ebb3480fff9b4d53e6
- https://ubuntu.com/security/notices/USN-4917-1
- https://www.openwall.com/lists/oss-security/2021/04/16/2
- https://www.zerodayinitiative.com/advisories/ZDI-21-422/
- https://launchpad.net/bugs/cve/CVE-2021-3492
- https://ubuntu.com/security/CVE-2021-3492
- https://www.openwall.com/lists/oss-security/2021/04/16/1
- https://security-tracker.debian.org/tracker/CVE-2021-3492
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3492
- https://nvd.nist.gov/vuln/detail/CVE-2021-3492
Frequently Asked Questions
What is the severity of CVE-2021-3492?
CVE-2021-3492 has a medium severity level due to potential memory issues leading to vulnerabilities.
How do I fix CVE-2021-3492?
You can fix CVE-2021-3492 by upgrading to the recommended kernel versions such as 5.10.223-1, 5.10.226-1, 6.1.119-1, 6.1.123-1, 6.12.11-1, or 6.12.12-1.
Which versions of Ubuntu are affected by CVE-2021-3492?
CVE-2021-3492 affects Ubuntu versions from 18.04 up to 20.10.
What type of vulnerabilities does CVE-2021-3492 introduce?
CVE-2021-3492 may introduce double-free situations or situations where memory is not freed, increasing the risk of an attack.
Is CVE-2021-3492 an issue with just Ubuntu?
CVE-2021-3492 specifically affects the Shiftfs stacking file system in Ubuntu Linux kernels.
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