Medium 5.5Published Aug 22, 2022

CVE-2021-3997A flaw was found in systemd.

Updated under an hour ago (Oct 27, 2026, 4:30 PM ET)

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It affects Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP and 5 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP

Exploited in the last 30 days

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.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-674
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: redhat
NVD analysis: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 14, 2026

Affected products

Affected products

Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.0 before V3.1.5	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.0 before V3.1.5	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.0 before V3.1.5	CISA ADP
systemd_project systemd systemd_project:systemd	from 240 before 250.2	NVD
fedoraproject fedora fedoraproject:fedora	34; 35	NVD
redhat enterprise_linux redhat:enterprise_linux	7.0; 8.0; 9.0	NVD

References

References

https://bugzilla.redhat.com/show_bug.cgi?id=2024639	issue-tracking, patch, third-party-advisory
https://www.openwall.com/lists/oss-security/2022/01/10/2	exploit, mailing-list, third-party-advisory
https://github.com/systemd/systemd/commit/5b1cf7a9be37e20133c0208005274ce4a5b5c6a1	patch, third-party-advisory
https://access.redhat.com/security/cve/CVE-2021-3997	issue-tracking, third-party-advisory
https://security.gentoo.org/glsa/202305-15	vendor-advisory
https://cert-portal.siemens.com/productcert/html/ssa-398330.html

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.