CVE-2020-16127

accountsservice .pam_environment infinite loop

Severity Score

5.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

An Ubuntu-specific modification to AccountsService in versions before 0.6.55-0ubuntu13.2, among other earlier versions, would perform unbounded read operations on user-controlled ~/.pam_environment files, allowing an infinite loop if /dev/zero is symlinked to this location.

Una modificación específica de Ubuntu para AccountsService en versiones anteriores a 0.6.55-0ubuntu13.2, entre otras versiones anteriores, llevaría a cabo operaciones de lectura ilimitadas en archivos ~/.pam_environment controlados por el usuario, permitiendo un bucle infinito si /dev/zero está enlazado simbólicamente a esta ubicación

Kevin Backhouse discovered that AccountsService incorrectly dropped privileges. A local user could possibly use this issue to cause AccountsService to crash or hang, resulting in a denial of service. Kevin Backhouse discovered that AccountsService incorrectly handled reading .pam_environment files. A local user could possibly use this issue to cause AccountsService to crash or hang, resulting in a denial of service. This issue only affected Ubuntu 20.04 LTS and Ubuntu 20.10. Various other issues were also addressed.

*Credits: Kevin Backhouse

CVSS Scores

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2020-07-29 CVE Reserved
2020-11-03 CVE Published
2024-09-16 CVE Updated
2024-09-16 First Exploit
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-20: Improper Input Validation
CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')

CAPEC

References (1)

URL	Tag	Source

URL	Date	SRC
https://securitylab.github.com/advisories/GHSL-2020-187-accountsservice-drop-privs-DOS	2024-09-16

URL	Date	SRC

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Freedesktop Search vendor "Freedesktop"		Accountsservice Search vendor "Freedesktop" for product "Accountsservice"				< 0.6.55 Search vendor "Freedesktop" for product "Accountsservice" and version " < 0.6.55"		-		Affected