CVE-2021-25659

mediumpriority · track · 30EPSS 0.010 · 64 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.04% (64th) EPSS

CVSS 5 · medium

Is it mine?

9 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · cisa_csaf_ot · nvd

EPSS · scored 2026-10-27

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.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

FixedAutomation License Manager 6siemens_psirt
Update to V6.0 SP9 Update 2 or later
https://support.industry.siemens.com/cs/ww/en/view/114358/
FixedAutomation License Manager 6cisa_csaf_ot
Update to V6.0 SP9 Update 2 or later
https://support.industry.siemens.com/cs/ww/en/view/114358/
MitigationAutomation License Manager 5siemens_psirt
If remote connections are needed, limit remote access to port 4410/tcp to trusted systems only
MitigationAutomation License Manager 6siemens_psirt
If remote connections are needed, limit remote access to port 4410/tcp to trusted systems only
MitigationAutomation License Manager 5cisa_csaf_ot
If remote connections are needed, limit remote access to port 4410/tcp to trusted systems only
MitigationAutomation License Manager 6cisa_csaf_ot
If remote connections are needed, limit remote access to port 4410/tcp to trusted systems only
No fix availableAutomation License Manager 5siemens_psirt
Currently no remediation is available
No fix availableAutomation License Manager 5cisa_csaf_ot
Currently no remediation is available

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5

v2.05mediumAV:N/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 10 · impact 2.9

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 3.6

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:Csecondary · CISA US

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:Csecondary · Siemens ProductCERT DE

v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-400USprimaryCWE-400USCWE-400US

affected products (9)

Products and version ranges known to be affected.

Automation License Manager 5all versionscisa_csaf_otUS
Automation License Manager 6all versionscisa_csaf_otUS
Siemens Automation License Manager 5≤ vers:all/*cisa_csaf_otUS
Siemens Automation License Manager 6< V6.0_SP9_Update_2cisa_csaf_otUS
Siemens Automation License Manager 5≤ All versionsenisa_euvdEU
Siemens Automation License Manager 6All versions → V6.0 SP9 Update 2enisa_euvdEU
siemens automation license manager5.0.0 → 6.0.9nvdUScpe:2.3:a:siemens:automation_license_manager:*:*:*:*:*:*:*:*
Siemens Automation License Manager 5≤ vers:all/*siemens_psirtDE
Siemens Automation License Manager 6< V6.0 SP9 Update 2siemens_psirtDE

advisories (2)

Vendor and ecosystem advisories describing this.

SSA-158827SSA-158827: Denial-of-Service Vulnerability in Automation License Manager2021-08-10csaf · siemens_psirtDE
A vulnerability was identified in the Automation License Manager software that could be triggered by sending specially crafted packets to port 4410/tcp of an affected system. This could cause a denial-of-service preventing legitimate users from using the system. Siemens has released an update for the Automation License Manager 6 and recommends to update to the latest version. Siemens recommends specific countermeasures for products where updates are not, or not yet available.
ICSA-21-222-02Siemens Automation License Manager2021-08-10icsa · cisa_csaf_otUS
A vulnerability was identified in the Automation License Manager software that could be triggered by sending specially crafted packets to port 4410/tcp of an affected system. This could cause a denial-of-service preventing legitimate users from using the system. Siemens has released an update for the Automation License Manager 6 and recommends to update to the latest version. Siemens recommends specific countermeasures for products where updates are not, or not yet available.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cisa_csaf_ot nvd siemens_psirt NVD CVE.org MITRE

published 2021-08-10modified 2026-06-17

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+9613 more

references (6)

External citations — patches, advisories, analysis.

scry

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