Stack-based Buffer Overflow Affecting shim-x64 package, versions <0:15.4-2.el8_1


Severity

Recommended
medium

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-RHEL8-SHIMX64-3976034
  • published26 Jul 2021
  • disclosed2 Mar 2021

Introduced: 2 Mar 2021

CVE-2020-27749  (opens in a new tab)
CWE-121  (opens in a new tab)

How to fix?

Upgrade RHEL:8 shim-x64 to version 0:15.4-2.el8_1 or higher.
This issue was patched in RHSA-2021:2790.

NVD Description

Note: Versions mentioned in the description apply only to the upstream shim-x64 package and not the shim-x64 package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

A flaw was found in grub2 in versions prior to 2.06. Variable names present are expanded in the supplied command line into their corresponding variable contents, using a 1kB stack buffer for temporary storage, without sufficient bounds checking. If the function is called with a command line that references a variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack frame and control execution which could also circumvent Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

CVSS Scores

version 3.1