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Fencer Intel
medium 4.5

CVE-2019-3842 json

In systemd before v242-rc4, it was discovered that pam_systemd does not properly sanitize the environment before using the XDG_SEAT variabl…

published 7y ago modified 4mo ago also EUVD-2019-13462

cvss
4.5
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits
1
Exploit-DB

Summary

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".

Patch / fix

  • systemd Debian 14, Debian 13, Debian 12 241-3

debian advisories DEBIAN-CVE-2019-3842

  • systemd Ubuntu 14.04 LTS 204-5ubuntu20.31
  • systemd Ubuntu 16.04 LTS 229-4ubuntu21.21
  • systemd Ubuntu 18.04 LTS 237-3ubuntu10.19

ubuntu advisories UBUNTU-CVE-2019-3842

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • systemd RHEL 8 239-45.el8
  • systemd-pam RHEL 8 239-45.el8
  • systemd-libs RHEL 8 239-45.el8
  • systemd-udev RHEL 8 239-45.el8
  • systemd-tests RHEL 8 239-45.el8
  • systemd-container RHEL 8 239-45.el8
  • systemd-journal-remote RHEL 8 239-45.el8
  • systemd RHEL 8.2 EUS 239-31.el8_2.7

red hat advisories RHSA-2021:3900RHSA-2021:1611

  • systemd SLE Module for Basesystem 15 SP1, SLE Module for Basesystem 15 234-24.30.1
  • systemd SLES for SAP 12 SP4, SLES for SAP 12 SP3, SLES for SAP 12 SP2 +10 more 228-150.66.4

suse advisories SUSE-SU-2019:1364-2SUSE-SU-2019:1364-1SUSE-SU-2019:1265-1

  • systemd openSUSE Tumbleweed 249.4-2.2

opensuse advisories openSUSE-SU-2024:11420-1

  • systemd Rocky Linux 8 239-45.el8

rocky linux advisories RLSA-2021:1611

Is CVE-2019-3842 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-3842 updated cvss 4.5

systemd: Spoofing of XDG_SEAT allows for actions to be checked against "allow_active" instead of "allow_any"

  • Red Hat Enterprise Linux 7 systemd, libgudev1, systemd-libs, systemd-sysv, systemd-python, systemd-networkd, +2 more
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux BaseOS (v. 8) systemd 239-45.el8, systemd-pam 239-45.el8, systemd-libs 239-45.el8, systemd-udev 239-45.el8, systemd-tests 239-45.el8, systemd-container 239-45.el8, +1 more
    fixed: vendor fix RHSA-2021:1611
  • Red Hat Enterprise Linux BaseOS EUS (v. 8.2) systemd 239-31.el8_2.7, systemd-pam 239-31.el8_2.7, systemd-libs 239-31.el8_2.7, systemd-udev 239-31.el8_2.7, systemd-tests 239-31.el8_2.7, systemd-container 239-31.el8_2.7, +1 more
    fixed: vendor fix RHSA-2021:3900

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. Published
  2. First public exploit (EDB-46743)

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

1.21% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • EDB-46743 systemd - Lack of Seat Verification in PAM Module Permits Spoofing Active Session to polkit dos, 2019-04-23
  • packetstormsecurity.com http://packetstormsecurity.com/files/152610/systemd-Seat-Verification-Active-Session-Spoofing.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 4.5 CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
NVD 3.1 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 4.4 AV:L/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • The systemd Project systemd

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.