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Vulnerability record · CVE-2021-25659 · published 10 August 2021

CVE-2021-25659: Siemens automation license manager uncontrolled resource consumption vulnerability

Siemens · Automation License Manager

A vulnerability has been identified in Automation License Manager 5 (All versions), Automation License Manager 6 (All versions < V6.0 SP9 Update 2). Sending specially crafted packets to port 4410/tcp of an affected system could lead to extensive memory being consumed and as such could cause a denial-of-service preventing legitimate users from using the system.

7.5 CVSS 3.1 High EPSS 1.0% · top 37.5% CWE-400 · Uncontrolled resource consumption
7.5CVSS 3.1 base score, v2 5.0
1.0%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

A vulnerability has been identified in Automation License Manager 5 (All versions), Automation License Manager 6 (All versions < V6.0 SP9 Update 2). Sending specially crafted packets to port 4410/tcp of an affected system could lead to extensive memory being consumed and as such could cause a denial-of-service preventing legitimate users from using the system.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://cert-portal.siemens.com/productcert/pdf/ssa-158827.pdf PatchVendor Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-158827.pdf PatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-25659), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.