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8.8 High Exploited

CVE-2021-3493 Linux Kernel Privilege Escalation Vulnerability

Active exploitation observed

· CISA KEV catalogue
Required action Apply updates per vendor instructions.
Ransomware campaigns Not observed so far
Weakness CWE-862

Description

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.

Affected products and versions

Product Affected versions Fixed in
Linux kernel 5.8 earliest → < 5.8.0-50.56 5.8.0-50.56
Linux kernel 5.4 earliest → < 5.4.0-72.80 5.4.0-72.80
Linux kernel 4.15 earliest → < 4.15.0-142.146 4.15.0-142.146
Linux kernel 4.4 earliest → < 4.4.0-209.241 4.4.0-209.241

References

Timeline

  1. Published
  2. Added to the KEV catalogue
  3. Last modified

Other CVEs of Linux kernel

The 3 CVEs of Linux kernel →
CVE-2021-3492 Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle faults… 8.8 High CVE-2019-15794 Overlayfs in the Linux kernel and shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3… 7.1 High
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