An unauthenticated remote attacker could create a permanent denial-of-service condition by sending specially crafted OSPF packets.

published 2021-05-12 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-20852

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.6%; EPSS 1.6% chance of exploitation in 30 days, percentile 76%
public exploits: 0; none known

An unauthenticated remote attacker could create a permanent denial-of-service condition by sending specially crafted OSPF packets. Successful exploitation requires OSPF to be enabled on an affected device on the SCALANCE XM-400, XR-500 (All versions prior to v6.4).

Patch / fix

fixed in 11

siemens scalance_xm-400_firmware 6.4
siemens scalance_xr524_firmware 6.4
siemens scalance_xr526_firmware 6.4
siemens scalance_xr528_firmware 6.4
siemens scalance_xr552_firmware 6.4
siemens scalance_xm416-4c_firmware 6.4
siemens scalance_xm408-8c_firmware 6.4
siemens scalance_xm408-4c_firmware 6.4
siemens scalance_xm416-4c_l3_firmware 6.4
siemens scalance_xm408-8c_l3_firmware 6.4
siemens scalance_xm408-4c_l3_firmware 6.4

Vendor advisories

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

cisa ICSA-21-131-10 updated 2025-05-06 cvss 7.5

Siemens SCALANCE XM-400 and XR-500 Devices

Siemens SCALANCE XM-400 Family <V6.4
affected: fixed in V6.4, mitigation support.industry.siemens.com
Siemens SCALANCE XR-500 Family <V6.4
affected: fixed in V6.4, 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

1.63% chance of exploitation in the next 30 days, higher than 76% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	7.1	AV:N/AC:M/Au:N/C:N/I:N/A:C

Affected products

n/a SCALANCE XM-400, XR-500

Classification

Weakness

CWE-682 Incorrect Calculation

References

cert-portal.siemens.com /productcert/pdf/ssa-116379.pdf
vendor-advisory
us-cert.cisa.gov /ics/advisories/icsa-21-131-10
third-party-advisory, us-government-resource

Sources

CVE List CVE-2020-28393
NVD CVE-2020-28393

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.

Summary