Skip to content
Fencer Vulns
medium 5.5

CVE-2021-3997 json

A flaw was found in systemd.

published 2022-08-23 4 y ago modified 2026-11-02 6 d ago also EUVD-2021-27187

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.7%
EPSS 1.7% chance of exploitation in 30 days, percentile 77%
public exploits
0
none known

Summary

A flaw was found in systemd. An uncontrolled recursion in systemd-tmpfiles may lead to a denial of service at boot time when too many nested directories are created in /tmp.

Patch / fix

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • systemd Debian 14, Debian 13, Debian 12 250.2-1

debian advisories DEBIAN-CVE-2021-3997

  • systemd Ubuntu 20.04 LTS 245.4-4ubuntu3.15

ubuntu advisories UBUNTU-CVE-2021-3997

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 SLE Module for Basesystem 15 SP3, SLE Micro 5.1 246.16-150300.7.39.1
  • systemd SLE Module for Basesystem 15 SP3, SLE Micro 5.1 246.16-7.33.1

suse advisories SUSE-SU-2022:0539-1SUSE-SU-2022:0043-1

  • systemd openSUSE Tumbleweed 249.7-3.1
  • systemd openSUSE Leap 15.3 246.16-150300.7.39.1
  • systemd openSUSE Leap 15.3 246.16-7.33.1
  • htmldoc Package Hub 15 SP3, openSUSE Leap 15.3 1.9.12-bp153.2.6.1

opensuse advisories openSUSE-SU-2024:11731-1openSUSE-SU-2022:0539-1openSUSE-SU-2022:0043-1

  • systemd CBL-Mariner 2.0 250.3-21

azure linux advisories AZL-10638

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2021-3997 updated cvss 5.5

systemd: Uncontrolled recursion in systemd-tmpfiles when removing files

  • Red Hat Enterprise Linux 7 systemd, libgudev1, systemd-libs, systemd-sysv, systemd-python, systemd-networkd, +2 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 systemd, systemd-pam, systemd-libs, systemd-udev, systemd-tests, systemd-container, +1 more
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 9 systemd, systemd-pam, systemd-libs, systemd-oomd, systemd-udev, systemd-ukify, +6 more
    not affected: vulnerable code not present

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

cisa ICSA-23-348-10 updated cvss 5.5

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
31 d ago

Exploit prediction

1.74% chance of exploitation in the next 30 days, higher than 77% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • openwall.com https://www.openwall.com/lists/oss-security/2022/01/10/2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • n/a systemd
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness

References

Sources

Fencer Vulns 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.