Junglewise Threat Intelligence

CVE-2021-3493: Linux Kernel Privilege Escalation Vulnerability

CVE-2021-3493 · Severity: critical · CVSS 7.8 · Exploited in the wild · Published 2022-10-20

Technologies: Linux Kernel. Vendors: Linux.

Executive brief

The overlayfs implementation in the Linux kernel fails to properly validate file capabilities against user namespaces. When combined with unprivileged user namespaces and specific Ubuntu kernel patches allowing unprivileged overlay mounts, a local attacker can gain elevated privileges.

Affected products

  • Linux Linux Kernel Ubuntu kernel patches for unprivileged overlay mounts

Timeline

  • 2021-04-16: disclosed: Public disclosure on oss-security mailing list
  • 2022-10-20: kev added: Added to CISA Known Exploited Vulnerabilities Catalog

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