CVE-2017-8900

Ubuntu Security Notice USN-3285-1

Severity Score

4.6

*CVSS v3

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

LightDM through 1.22.0, when systemd is used in Ubuntu 16.10 and 17.x, allows physically proximate attackers to bypass intended AppArmor restrictions and visit the home directories of arbitrary users by establishing a guest session.

LightDM hasta la versión 1.22.0, cuando es usado systemd en Ubuntu versión 16.10 y versiones 17.x, permite a los atacantes físicamente cercanos omitir las restricciones previstas de AppArmor y visitar los directorios principales de usuarios arbitrarios mediante el establecimiento de una sesión de invitado.

Tyler Hicks discovered that LightDM did not confine the user session for guest users. An attacker with physical access could use this issue to access files and other resources that they should not be able to access. In the default installation, this includes files in the home directories of other users on the system. This update fixes the issue by disabling the guest session. It may be re-enabled in a future update.

*Credits: N/A

Attack Vector

Physical

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

None

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2017-05-11 CVE Reserved
2017-05-12 CVE Published
2024-08-05 CVE Updated
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (4)

URL	Tag	Source
http://www.securityfocus.com/bid/98554	Third Party Advisory

URL	Date	SRC

URL	Date	SRC
https://launchpad.net/bugs/1663157	2019-10-03
https://people.canonical.com/~ubuntu-security/cve/2017/CVE-2017-8900.html	2019-10-03
https://www.ubuntu.com/usn/usn-3285-1	2019-10-03

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Lightdm Project Search vendor "Lightdm Project"	Lightdm Search vendor "Lightdm Project" for product "Lightdm"	<= 1.22.0 Search vendor "Lightdm Project" for product "Lightdm" and version " <= 1.22.0"	-	Affected	in	Canonical Search vendor "Canonical"	Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"	16.10 Search vendor "Canonical" for product "Ubuntu Linux" and version "16.10"	-	Safe
Lightdm Project Search vendor "Lightdm Project"	Lightdm Search vendor "Lightdm Project" for product "Lightdm"	<= 1.22.0 Search vendor "Lightdm Project" for product "Lightdm" and version " <= 1.22.0"	-	Affected	in	Canonical Search vendor "Canonical"	Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"	17.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "17.04"	-	Safe