CVE-2021-3492
Ubuntu linux kernel shiftfs file system double free vulnerability
- Published
- Apr 17, 2021
- Updated
- Sep 17, 2024
- Assigning CNA
- canonical
- Evidence observed
- Aug 5, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HLow · next 30 days
- Percentile
- 73.3%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
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.
Sources
1PoC for CVE-2021-3492 used at Pwn2Own 2021
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