CVE-2020-27777

Description

A flaw was found in the way RTAS handled memory accesses in userspace to kernel communication. On a locked down (usually due to Secure Boot) guest system running on top of PowerVM or KVM hypervisors (pseries platform) a root like local user could use this flaw to further increase their privileges to that of a running kernel.

CVSS Metrics

• v3.1•MEDIUM•Score: 6.7CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
• v2.0•HIGH•Score: 7.2AV:L/AC:L/Au:N/C:C/I:C/A:C

EPSS Trends

Current EPSS score: 0.03%• Percentile: 8%

Techniques & Countermeasures

• CWE-862•Missing Authorization

  The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

Affected Systems

• linux•linux_kernel

  < 4.14.204 | ≥ 4.15, < 4.19.155 | ≥ 4.20, < 5.4.75 | ≥ 5.5, < 5.9.5

• redhat•enterprise_linux

  5.0 | 6.0 | 7.0 | 8.0

• redhat•openshift_container_platform

  4.4 | 4.5 | 4.6

References (4)

• https://bugzilla.redhat.com/show_bug.cgi?id=1900844
• https://www.openwall.com/lists/oss-security/2020/10/09/1
• https://www.openwall.com/lists/oss-security/2020/11/23/2
• https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=next&id=bd59380c5ba4147dcbaad3e582b55ccfd120b764