Vulnerability in Ubuntu Linux Kernel
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…
EPSS: 0.797 (99.1th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
Affected products
- Ubuntu Linux Kernel — versions 5.8 kernel, 5.4 kernel, 4.15 kernel
Weakness classification (CWE)
CISA KEV (Known Exploited Vulnerabilities)
This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.
BOD 22-01 due date: .
Required action: Apply updates per vendor instructions.
Public proof-of-concept exploits
References
- ubuntu.com/security/notices/USN-4917-1 (x_refsource_MISC)
- git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/ (x_refsource_MISC)
- www.openwall.com/lists/oss-security/2021/04/16/1 (x_refsource_MISC)
- packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076… (x_refsource_MISC)
- packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalatio… (x_refsource_MISC)
- packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalatio… (x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-3493?
- CVE-2021-3493 is a high-severity vulnerability in Ubuntu Linux Kernel, classified under Privilege Context Switching Error. CVSS score: 8.8/10. Published 2021-04-17.
- How severe is CVE-2021-3493?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2021-3493 known to be exploited?
- Yes. CVE-2021-3493 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-10-20), indicating it is being actively exploited. 211 public proof-of-concept repositories are indexed.