CVE-2019-3842 Security feature bypass in systemd

What is CVE-2019-3842?

CVE-2019-3842 is a medium-severity vulnerability in Debian Debian Linux, published on 9 Apr 2019. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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".

Weakness: CWE-863, CWE-285

Which versions are affected by CVE-2019-3842?

It affects 4 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Redhat Enterprise Linux, Systemd Project Systemd.

How do I fix CVE-2019-3842?

Upgrade to a fixed version.

Is CVE-2019-3842 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2019-3842 exists.

Public exploit code: 1 Exploit-DB entry.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2019-3842, DSA-4428-1, GHSA-c23j-qp89-q76c, UBUNTU-CVE-2019-3842, USN-3938-1.