USN-4916-1: Linux kernel vulnerabilities | Cloud Foundry

Severity

High

Vendor

Canonical Ubuntu

Versions Affected

• Canonical Ubuntu 14.04
• Canonical Ubuntu 16.04

Description

It was discovered that the overlayfs implementation in the Linux kernel did not properly validate the application of file system capabilities with respect to user namespaces. A local attacker could use this to gain elevated privileges. (CVE-2021-3493)

Piotr Krysiuk discovered that the BPF JIT compiler for x86 in the Linux kernel did not properly validate computation of branch displacements in some situations. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-29154)

CVEs contained in this USN include: CVE-2021-29154, CVE-2021-3493.

Affected Cloud Foundry Products and Versions

Severity is high unless otherwise noted.

• Xenial Stemcells
  • 456.x versions prior to 456.158
  • 621.x versions prior to 621.123
  • All other stemcells not listed.

Mitigation

Users of affected products are strongly encouraged to follow the mitigations below. The Cloud Foundry project recommends upgrading the following releases:

• Xenial Stemcells
  • Upgrade 456.x versions to 456.158 or greater
  • Upgrade 621.x versions to 621.123 or greater
  • All other stemcells should be upgraded to the latest version available on bosh.io.

References

• USN Notice
• CVE-2021-29154
• CVE-2021-3493

History

2021-04-29: Initial vulnerability report published.