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USN-3836-2: Linux kernel (HWE) vulnerabilities


Severity

Medium

Vendor

Canonical Ubuntu

Versions Affected
  • Canonical Ubuntu 16.04
Description

USN-3836-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04 LTS. This update provides the corresponding updates for the Linux Hardware Enablement (HWE) kernel from Ubuntu 18.04 LTS for Ubuntu 16.04 LTS.

Jann Horn discovered that the Linux kernel mishandles mapping UID or GID ranges inside nested user namespaces in some situations. A local attacker could use this to bypass access controls on resources outside the namespace. (CVE-2018-18955)

Philipp Wendler discovered that the overlayfs implementation in the Linux kernel did not properly verify the directory contents permissions from within a unprivileged user namespace. A local attacker could use this to expose sensitive information (protected file names). (CVE-2018-6559)

CVEs contained in this USN include: CVE-2018-18955, CVE-2018-6559

Affected Pivotal Products and Versions

Severity is medium unless otherwise noted.

  • Vulnerable Cloud Foundry components individually listed here.
  • Impacted stemcells may be updated independently of upgrading Pivotal Application Service or PCF Isolation Segment.
  • Pivotal Application Service includes vulnerable stemcells in the following releases:
    • 2.4.x versions prior to 2.4.1
    • 2.3.x versions prior to 2.3.5
  • PCF Isolation Segment includes vulnerable stemcells in the following releases:
    • 2.4.x versions prior to 2.4.1
    • 2.3.x versions prior to 2.3.5
  • Pivotal Operations Manager is vulnerable in the following releases:
    • 2.4.x versions prior to 2.4.3
    • 2.3.x versions prior to 2.3.7
Mitigation

Users of affected versions should apply the following mitigation:

  • The Cloud Foundry security team recommends upgrading BOSH to the affected OSS components listed here if applicable.
  • Upgrade Pivotal products that use earlier versions of CF components to new Pivotal releases using new versions linked above. On the Pivotal Network product page for each release, check the Depends On section and/or Release Notes for this information.
  • Releases that have fixed this issue include:
    • Pivotal Application Service: 2.4.1, 2.3.5
    • PCF Isolation Segment: 2.4.1, 2.3.5
    • Pivotal Operations Manager: 2.4.3, 2.3.7
References
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