CVE-2021-3493 — Linux Kernel Privilege Escalation Vulnerability
Overview
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.
Vulnerability details
- CVE ID
- CVE-2021-3493
- Vulnerability
- Linux Kernel Privilege Escalation Vulnerability
- Vendor
- Linux
- Affected products
- Linux: Kernel
- Severity
- HIGH
- Exploitation status
- Actively exploited in the wild (CISA KEV)
- Published
- 2022-10-20
Remediation guidance
CVE-2021-3493 is in CISA's Known Exploited Vulnerabilities (KEV) catalog — U.S. federal civilian agencies are required to remediate it under Binding Operational Directive 22-01. Treat it as a priority for every environment.
Apply the vendor's official security update for Linux the affected product as soon as possible. Where a patch is unavailable, apply vendor mitigations or isolate/segment exposed systems.
Hunt for indicators of compromise tied to this vulnerability and confirm logging/EDR coverage on affected assets.
Authoritative references
Remediate CVE-2021-3493 — and stay ahead of the next one
CVE-2021-3493 is listed in the CISA KEV catalog as actively exploited — treat remediation as urgent. Scan your domain free to see whether CVE-2021-3493 and other Linux issues affect you and get a prioritized remediation report (full report from ₹999) — or stream the full feed of 1,600+ actively-exploited CVEs straight into your SOC.
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