Answer in brief
CVE-2021-3493 records a High severity vulnerability in CVE Program Container. The current sources mark it as known exploited. The current feed maps Ubuntu/linux kernel (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Ubuntu/linux kernel (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Ubuntu/linux kernelgeneric | >=5.8 kernel <5.8.0-50.56 || >=5.4 kernel <5.4.0-72.80 || >=4.15 kernel <4.15.0-142.146 || >=4.4 kernel <4.4.0-209.241 | 5.8.0-50.56, 5.4.0-72.80, 4.15.0-142.146, 4.4.0-209.241 |
Published upstream
Apr 17, 2021
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 21, 2025
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Oct 20, 2022
Evidence: source:kev:kev:kev:recordThe 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.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2021-3493 records a High severity vulnerability in CVE Program Container. The current sources mark it as known exploited. The current feed maps Ubuntu/linux kernel (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Ubuntu/linux kernel (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Ubuntu/linux kernelgeneric | >=5.8 kernel <5.8.0-50.56 || >=5.4 kernel <5.4.0-72.80 || >=4.15 kernel <4.15.0-142.146 || >=4.4 kernel <4.4.0-209.241 | 5.8.0-50.56, 5.4.0-72.80, 4.15.0-142.146, 4.4.0-209.241 |
Published upstream
Apr 17, 2021
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 21, 2025
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Oct 20, 2022
Evidence: source:kev:kev:kev:recordThe 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.
Quoted source text, attributed separately from HOL analysis.