systemd up to v242-rc3 pam_systemd XDG_SEAT access control

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.9$0-$5k0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in systemd up to v242-rc3. The affected element is an unknown function of the component pam_systemd. The manipulation of the argument XDG_SEAT as part of Environment Variable results in access control. This vulnerability is known as CVE-2019-3842. Attacking locally is a requirement. Furthermore, an exploit is available. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability was found in systemd up to v242-rc3. It has been classified as critical. Affected is an unknown functionality of the component pam_systemd. The manipulation of the argument XDG_SEAT as part of a Environment Variable leads to a access control vulnerability. CWE is classifying the issue as CWE-264. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In systemd before v242-rc4, it was discovered that pam_systemd does not properly sanitize the environment before using the XDG_SEAT variable. It is possible for an attacker, in some particular configurations, to set a XDG_SEAT environment variable which allows for commands to be checked against polkit policies using the "allow_active" element rather than "allow_any".

The bug was discovered 04/08/2019. The weakness was published 04/09/2019 by Chris Coulson as confirmed bug report (Bugzilla). The advisory is shared for download at bugzilla.redhat.com. This vulnerability is traded as CVE-2019-3842 since 01/03/2019. The attack needs to be approached locally. The exploitation doesn't require any form of authentication. Technical details and a public exploit are known. The MITRE ATT&CK project declares the attack technique as T1068.

The exploit is shared for download at packetstormsecurity.com. It is declared as proof-of-concept. The vulnerability was handled as a non-public zero-day exploit for at least 1 days. During that time the estimated underground price was around $5k-$25k. The vulnerability scanner Nessus provides a plugin with the ID 236564 (Alibaba Cloud Linux 3 : 0039: systemd (ALINUX3-SA-2022:0039)), which helps to determine the existence of the flaw in a target environment. The commercial vulnerability scanner Qualys is able to test this issue with plugin 176866 (Debian Security Update for systemd (DLA 1762-1)).

Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the databases at Tenable (236564) and SecurityFocus (BID 107081†). Similar entries are available at VDB-112610, VDB-113214 and VDB-132015. Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.2
VulDB Meta Temp Score: 5.9

VulDB Base Score: 7.0
VulDB Temp Score: 6.3
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.0
NVD Vector: 🔍

CNA Base Score: 4.5
CNA Vector (Red Hat, Inc.): 🔍

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Access control
CWE: CWE-264
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: No

Availability: 🔍
Access: Public
Status: Proof-of-Concept
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Nessus ID: 236564
Nessus Name: Alibaba Cloud Linux 3 : 0039: systemd (ALINUX3-SA-2022:0039)

Qualys ID: 🔍
Qualys Name: 🔍

Exploit-DB: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔍

Patch: github.com

Timelineinfo

01/03/2019 🔍
02/18/2019 +46 days 🔍
04/08/2019 +49 days 🔍
04/09/2019 +1 days 🔍
04/10/2019 +1 days 🔍
05/21/2025 +2233 days 🔍

Sourcesinfo

Product: github.com

Advisory: 152610
Researcher: Chris Coulson
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2019-3842 (🔍)
GCVE (CVE): GCVE-0-2019-3842
GCVE (VulDB): GCVE-100-133260
SecurityFocus: 107081 - systemd CVE-2019-6454 Local Denial of Service Vulnerability

scip Labs: https://www.scip.ch/en/?labs.20161013
See also: 🔍

Entryinfo

Created: 04/10/2019 09:44
Updated: 05/21/2025 21:09
Changes: 04/10/2019 09:44 (64), 05/28/2020 14:53 (5), 08/28/2023 09:33 (5), 08/28/2023 09:34 (13), 06/13/2024 08:48 (22), 05/21/2025 21:09 (2)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Interested in the pricing of exploits?

See the underground prices here!