CVE-2018-6557

Publication date 21 August 2018

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

The MOTD update script in the base-files package in Ubuntu 18.04 LTS before 10.1ubuntu2.2, and Ubuntu 18.10 before 10.1ubuntu6 incorrectly handled temporary files. A local attacker could use this issue to cause a denial of service, or possibly escalate privileges if kernel symlink restrictions were disabled.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
base-files	18.04 LTS bionic	Fixed 10.1ubuntu2.2
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

mdeslaur

low priority because of default symlink restrictions

Severity score breakdown

Parameter	Value
Base score	7.0 · High
Attack vector	Local
Attack complexity	High
Privileges required	Low
User interaction	None
Scope	Unchanged
Confidentiality	High
Integrity impact	High
Availability impact	High
Vector	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

USN-3748-1
base-files vulnerability
21 August 2018