USN-4318-1: Linux kernel vulnerabilities

Severity

Medium

Vendor

Canonical Ubuntu

Description

Al Viro discovered that the vfs layer in the Linux kernel contained a use- after-free vulnerability. A local attacker could use this to cause a denial of service (system crash) or possibly expose sensitive information (kernel memory). (CVE-2020-8428)

Gustavo Romero and Paul Mackerras discovered that the KVM implementation in the Linux kernel for PowerPC processors did not properly keep guest state separate from host state. A local attacker in a KVM guest could use this to cause a denial of service (host system crash). (CVE-2020-8834)

Shijie Luo discovered that the ext4 file system implementation in the Linux kernel did not properly check for a too-large journal size. An attacker could use this to construct a malicious ext4 image that, when mounted, could cause a denial of service (soft lockup). (CVE-2020-8992)

CVEs contained in this USN include: CVE-2020-8428, CVE-2020-8834, CVE-2020-8992.

Affected Cloud Foundry Products and Versions

Severity is medium unless otherwise noted.

• Xenial Stemcells
  • 170.x versions prior to 170.215
  • 250.x versions prior to 250.196
  • 315.x versions prior to 315.179
  • 456.x versions prior to 456.108
  • 621.x versions prior to 621.69
  • 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 170.x versions to 170.215 or greater
  • Upgrade 250.x versions to 250.196 or greater
  • Upgrade 315.x versions to 315.179 or greater
  • Upgrade 456.x versions to 456.108 or greater
  • Upgrade 621.x versions to 621.69 or greater
  • All other stemcells should be upgraded to the latest version available on bosh.io.

History

2020-04-06: Initial vulnerability report published.