Linux Kernel Privilege Escalation Vulnerability
The overlayfs stacking file system in Linux kernel does not properly validate the application of file capabilities against user namespaces, which could lead to privilege escalation.
- Vendor
- Linux
- Product
- Kernel
- CVSS
- 8.8
- EPSS (exploit probability)
- 49.2%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2021-3493 being exploited?
Yes. CISA added CVE-2021-3493 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 49.2% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-10-19. Full cross-catalog view: /kev-comparison
What to do
CISA required actionApply updates per vendor instructions.
US federal civilian agencies must remediate by (21 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Linux Kernel CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2026-53266 Linux Kernel Out-of-Bounds Write Vulnerabilitywrite-up | [ HIGH ] | 8.8 | 0.8% | |
| CVE-2025-39964 Linux Kernel Race Condition Vulnerabilitywrite-up | [ HIGH ] | 7.8 | 1.4% | |
| CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerabilitywrite-up | [ CRITICAL ] | 9.8 | 2.9% | |
| CVE-2026-53362 Linux Kernel Unspecified Vulnerability | [ HIGH ] | 7.8 | 0.7% | |
| CVE-2022-0995 Linux Kernel Out-of-Bounds Write Vulnerability | [ HIGH ] | 7.8 | 8.9% | |
| CVE-2026-53264 Linux kernel traffic-control subsystem use-after-free racewrite-up | [ HIGH ] | 7.8 | 0.2% | — |
| CVE-2022-0492 Linux Kernel Improper Authentication Vulnerability | [ HIGH ] | 7.8 | 5.5% | |
| CVE-2026-31431 Linux Kernel Incorrect Resource Transfer Between Spheres Vulnerability | [ HIGH ] | 7.8 | 3.4% |