CVE-2021-3492
HIGHCVSS 7.8/10EPSS 1.55%
Last modified
CVE-2021-3492 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle faults occurring during copy_from_user() correctly. These could lead to either a double-free situation or memory not being freed at all. EPSS estimates a 1.55% chance of exploitation in the next 30 days.
Description
Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle faults occurring during copy_from_user() correctly. These could lead to either a double-free situation or memory not being freed at all. An attacker could use this to cause a denial of service (kernel memory exhaustion) or gain privileges via executing arbitrary code. AKA ZDI-CAN-13562.
Metrics
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Canonical | Ubuntu Linux | < 18.04 |
| Canonical | Ubuntu Linux | >= 18.04.1, < 20.04 |
| Canonical | Ubuntu Linux | < 20.10 |
References
- http://packetstormsecurity.com/files/162614/Kernel-Live-Patch-Security-Notice-LSN-0077-1.htmlThird Party Advisory, VDB Entry
- https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=25c891a949bf918b59cbc6e4932015ba4c35c333Mailing List, Patch, Vendor Advisory
- https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=8fee52ab9da87d82bc6de9ebb3480fff9b4d53e6Mailing List, Patch, Vendor Advisory
- https://ubuntu.com/security/notices/USN-4917-1Vendor Advisory
- https://www.openwall.com/lists/oss-security/2021/04/16/2Mailing List, Third Party Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-21-422/Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/162614/Kernel-Live-Patch-Security-Notice-LSN-0077-1.htmlThird Party Advisory, VDB Entry
- https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=25c891a949bf918b59cbc6e4932015ba4c35c333Mailing List, Patch, Vendor Advisory
- https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=8fee52ab9da87d82bc6de9ebb3480fff9b4d53e6Mailing List, Patch, Vendor Advisory
- https://ubuntu.com/security/notices/USN-4917-1Vendor Advisory
- https://www.openwall.com/lists/oss-security/2021/04/16/2Mailing List, Third Party Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-21-422/Third Party Advisory, VDB Entry
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-3492?
Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle faults occurring during copy_from_user() correctly. These could lead to either a double-free situation or memory not being freed at all. An attacker could use this to cause a denial of service (kernel memory exhaustion) or gain privileges via executing arbitrary code. AKA ZDI-CAN-13562.
How severe is CVE-2021-3492?
CVE-2021-3492 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 1.55% probability of exploitation in the next 30 days.
How do I fix CVE-2021-3492?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-3492?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST