Vulnerability Intelligence Report
Linux Kernel Privilege Escalation Vulnerability
CVE-2021-3493
The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.
CISA KEV
SSVC: Active Exploitation
CVSS Base Score
8.8
HIGH
Exploitability:2.1
Impact Score:6.1
EPSS Probability:43.99%
Executive Threat Verdict
Evaluating...
Evaluating Threat Landscape...
Assessing known weaponization, exploitation telemetry, and federal advisories.
Attack Surface
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Authentication
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Weaponization
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SSVC Action
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Weaknesses (CWE)
CWE-270 ↗CWE-270: Privilege Context Switching Error
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| Ubuntu | linux kernel | 5.8 kernel < 5.8.0-50.56 (affected), 5.4 kernel < 5.4.0-72.80 (affected), 4.15 kernel < 4.15.0-142.146 (affected), 4.4 kernel < 4.4.0-209.241 (affected) |
References & Technical Advisories
No reference links found.
Threat Intelligence Signals
Identity & Timeline
| Status | PUBLISHED |
| Assigning Authority | Canonical Ltd. · Vendor · UK |
| Reserved | 2021-04-12T00:00:00 |
| Published | 2021-04-17T04:20:16 |
| Patch Date | 2021-04-15 |
| Last Updated | 2025-10-21T23:25:48 |
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