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Fencer Vulns
medium 6.1

CVE-2020-13529 json

An exploitable denial-of-service vulnerability exists in Systemd 245.

published 2021-05-10 5 y ago modified 2026-10-14 26 d ago also EUVD-2020-5776

cvss
6.1
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 73%
public exploits
0
none known

Summary

An exploitable denial-of-service vulnerability exists in Systemd 245. A specially crafted DHCP FORCERENEW packet can cause a server running the DHCP client to be vulnerable to a DHCP ACK spoofing attack. An attacker can forge a pair of FORCERENEW and DCHP ACK packets to reconfigure the server.

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 12 249.4-2

debian advisories DEBIAN-CVE-2020-13529

  • systemd Ubuntu 18.04 LTS 237-3ubuntu10.49
  • systemd Ubuntu 20.04 LTS 245.4-4ubuntu3.10
  • systemd Ubuntu Pro 16.04 LTS 229-4ubuntu21.31+esm1

ubuntu advisories UBUNTU-CVE-2020-13529

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

  • NetworkManager RHEL 8 1:1.32.10-4.el8
  • NetworkManager-ovs RHEL 8 1:1.32.10-4.el8
  • NetworkManager-ppp RHEL 8 1:1.32.10-4.el8
  • NetworkManager-tui RHEL 8 1:1.32.10-4.el8
  • NetworkManager-adsl RHEL 8 1:1.32.10-4.el8
  • NetworkManager-team RHEL 8 1:1.32.10-4.el8
  • NetworkManager-wifi RHEL 8 1:1.32.10-4.el8
  • NetworkManager-wwan RHEL 8 1:1.32.10-4.el8

red hat advisories RHSA-2021:4361

  • systemd SLE Module for Basesystem 15 SP3 246.15-7.11.1

suse advisories SUSE-SU-2021:2809-1

  • NetworkManager openSUSE Tumbleweed 1.32.10-2.1
  • systemd openSUSE Tumbleweed 249.4-2.2
  • systemd openSUSE Leap 15.3 246.15-7.11.1

opensuse advisories openSUSE-SU-2024:10602-1openSUSE-SU-2024:11420-1openSUSE-SU-2021:2809-1

  • NetworkManager-cloud-setup AlmaLinux 8 1:1.32.10-4.el8

almalinux advisories ALSA-2021:4361

  • NetworkManager Rocky Linux 8 1:1.32.10-4.el8

rocky linux advisories RLSA-2021:4361

  • systemd Arch Linux 249-2

arch linux advisories AVG-1935

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-2020-13529 updated cvss 6.1

systemd: DHCP FORCERENEW authentication not implemented can cause a system running the DHCP client to have its network reconfigured

  • Red Hat Enterprise Linux 7 systemd, libgudev1, systemd-libs, systemd-sysv, NetworkManager, systemd-python, +16 more
    affected: workaround, no fix planned “There is no available mitigation for this issue.”
  • Red Hat CodeReady Linux Builder (v. 8) NetworkManager-debuginfo 1.32.10-4.el8, NetworkManager-debugsource 1.32.10-4.el8, NetworkManager-libnm-devel 1.32.10-4.el8, NetworkManager-ovs-debuginfo 1.32.10-4.el8, NetworkManager-ppp-debuginfo 1.32.10-4.el8, NetworkManager-tui-debuginfo 1.32.10-4.el8, +7 more Red Hat Enterprise Linux AppStream (v. 8) NetworkManager-cloud-setup 1.32.10-4.el8 Red Hat Enterprise Linux BaseOS (v. 8) NetworkManager 1.32.10-4.el8, NetworkManager-ovs 1.32.10-4.el8, NetworkManager-ppp 1.32.10-4.el8, NetworkManager-tui 1.32.10-4.el8, NetworkManager-adsl 1.32.10-4.el8, NetworkManager-team 1.32.10-4.el8, +7 more
    fixed: vendor fix “There is no available mitigation for this issue.” RHSA-2021:4361
  • Red Hat Enterprise Linux 8 systemd, systemd-pam, systemd-libs, systemd-udev, systemd-tests, systemd-container, +1 more Red Hat Enterprise Linux 9 systemd, systemd-pam, systemd-libs, systemd-oomd, systemd-udev, systemd-ukify, +21 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 6.1

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

Exploit prediction

1.43% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • talosintelligence.com https://talosintelligence.com/vulnerability_reports/TALOS-2020-1142 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 6.1 CVSS:3.0/AV:A/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD 3.1 6.1 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD 2.0 2.9 AV:A/AC:M/Au:N/C:N/I:N/A:P

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
  • CWE-290 Authentication Bypass by Spoofing

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.