CVE-2021-3493 (GCVE-0-2021-3493)

Vulnerability from cvelistv5 – Published: 2021-04-17 04:20 – Updated: 2025-10-21 23:25
VLAI? CISA
Summary
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.
Severity ?
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE
  • CWE-270 - Privilege Context Switching Error
Assigner
References
Impacted products
Vendor Product Version
Ubuntu linux kernel Affected: 5.8 kernel , < 5.8.0-50.56 (custom)
Affected: 5.4 kernel , < 5.4.0-72.80 (custom)
Affected: 4.15 kernel , < 4.15.0-142.146 (custom)
Affected: 4.4 kernel , < 4.4.0-209.241 (custom)
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Credits
An independent security researcher reporting to the SSD Secure Disclosure program
CISA Known Exploited Vulnerability
Data from the CISA Known Exploited Vulnerabilities Catalog

Date added: 2022-10-20

Due date: 2022-11-10

Required action: Apply updates per vendor instructions.

Used in ransomware: Unknown

Notes: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52; https://nvd.nist.gov/vuln/detail/CVE-2021-3493

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}


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Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.