CVE-2021-27395

mediumpriority · track · 32OT risk · elevatedEPSS 0.008 · 57 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.80% (57th) EPSS

CVSS 5.5 · medium

Is it mine?

20 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · cisa_csaf_ot · nvd

EPSS · scored 2026-10-28

A vulnerability has been identified in SIMATIC Process Historian 2013 and earlier (All versions), SIMATIC Process Historian 2014 (All versions < SP3 Update 6), SIMATIC Process Historian 2019 (All versions), SIMATIC Process Historian 2020 (All versions). An interface in the software that is used for critical functionalities lacks authentication, which could allow a malicious user to maliciously insert, modify or delete data.

remediations

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

A vendor fix is available.

FixedSIMATIC Process Historian 2014siemens_psirt
Update to SP3 Update 6 or later version
https://support.industry.siemens.com/cs/ww/en/view/109780528/
FixedSIMATIC Process Historian 2020siemens_psirt
To update, use the Process Historian version as bundled with PCS neo V3.1 Upd1 (https://support.industry.siemens.com/cs/ww/en/view/109804750/) or with PCS 7 V9.1 SP1 (https://support.industry.siemens.com/cs/ww/en/view/109805073/)
FixedSIMATIC Process Historian 2014cisa_csaf_ot
Update to SP3 Update 6 or later version
https://support.industry.siemens.com/cs/ww/en/view/109780528/
FixedSIMATIC Process Historian 2020cisa_csaf_ot
To update, use the Process Historian version as bundled with PCS neo V3.1 Upd1 (https://support.industry.siemens.com/cs/ww/en/view/109804750/) or with PCS 7 V9.1 SP1 (https://support.industry.siemens.com/cs/ww/en/view/109805073/)
MitigationSIMATIC Process Historian 2013 and earliersiemens_psirt
Consider upgrading to a newer SIMATIC Process Historian version
MitigationSIMATIC Process Historian 2014siemens_psirt
Deactivate following incoming rules in the local Windows firewall: - PH Redundancy Services - PH Wcf MessageQueue Service (RedundancyMaintenanceService) - PH Wcf MessageQueue Service (SqlMirroringSetup) - PH Wcf MessageQueue Service (MaintenanceService) - PH SQL-Server Mirroring Port (UDP) - PH SQL-Server Mirroring Port (TCP)
MitigationSIMATIC Process Historian 2019siemens_psirt
Consider upgrading to a newer SIMATIC Process Historian version
MitigationSIMATIC Process Historian 2020siemens_psirt
Deactivate following incoming rules in the local Windows firewall: - PH Redundancy Services - PH Wcf MessageQueue Service (RedundancyMaintenanceService) - PH Wcf MessageQueue Service (SqlMirroringSetup) - PH Wcf MessageQueue Service (MaintenanceService) - PH SQL-Server Mirroring Port (UDP) - PH SQL-Server Mirroring Port (TCP)
MitigationSIMATIC Process Historian 2013 and earliercisa_csaf_ot
Consider upgrading to a newer SIMATIC Process Historian version
MitigationSIMATIC Process Historian 2014cisa_csaf_ot
Deactivate following incoming rules in the local Windows firewall: - PH Redundancy Services - PH Wcf MessageQueue Service (RedundancyMaintenanceService) - PH Wcf MessageQueue Service (SqlMirroringSetup) - PH Wcf MessageQueue Service (MaintenanceService) - PH SQL-Server Mirroring Port (UDP) - PH SQL-Server Mirroring Port (TCP)
MitigationSIMATIC Process Historian 2019cisa_csaf_ot
Consider upgrading to a newer SIMATIC Process Historian version
MitigationSIMATIC Process Historian 2020cisa_csaf_ot
Deactivate following incoming rules in the local Windows firewall: - PH Redundancy Services - PH Wcf MessageQueue Service (RedundancyMaintenanceService) - PH Wcf MessageQueue Service (SqlMirroringSetup) - PH Wcf MessageQueue Service (MaintenanceService) - PH SQL-Server Mirroring Port (UDP) - PH SQL-Server Mirroring Port (TCP)
No fix plannedSIMATIC Process Historian 2013 and earliersiemens_psirt
Currently no remediation is planned
No fix plannedSIMATIC Process Historian 2019siemens_psirt
Currently no remediation is planned
No fix plannedSIMATIC Process Historian 2013 and earliercisa_csaf_ot
Currently no remediation is planned
No fix plannedSIMATIC Process Historian 2019cisa_csaf_ot
Currently no remediation is planned

cvss

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

9.8

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–critical · 5.5–9.8

v2.05.5mediumAV:N/AC:L/Au:S/C:N/I:P/A:Pprimary · NVD / NIST USexploitability 8 · impact 4.9

v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 5.2

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:Csecondary · CISA US

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:Csecondary · Siemens ProductCERT DE

v3.17.4highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-306USCWE-306USCWE-306US

affected products (20)

Products and version ranges known to be affected.

SIMATIC Process Historian 2013 and earlierall versionscisa_csaf_otUS
SIMATIC Process Historian 2014all versionscisa_csaf_otUS
SIMATIC Process Historian 2019all versionscisa_csaf_otUS
SIMATIC Process Historian 2020all versionscisa_csaf_otUS
Siemens SIMATIC Process Historian 2013 and earlier≤ vers:all/*cisa_csaf_otUS
Siemens SIMATIC Process Historian 2014< SP3_Update_6cisa_csaf_otUS
Siemens SIMATIC Process Historian 2019≤ vers:all/*cisa_csaf_otUS
Siemens SIMATIC Process Historian 2020≤ vers:all/*cisa_csaf_otUS
Siemens SIMATIC Process Historian 2013 and earlier≤ All versionsenisa_euvdEU
Siemens SIMATIC Process Historian 2014All versions → SP3 Update 6enisa_euvdEU
Siemens SIMATIC Process Historian 2019≤ All versionsenisa_euvdEU
Siemens SIMATIC Process Historian 2020≤ All versionsenisa_euvdEU
siemens simatic process historian 2013all versionsnvdUScpe:2.3:a:siemens:simatic_process_historian_2013:*:*:*:*:*:*:*:*
siemens simatic process historian 2014all versionsnvdUScpe:2.3:a:siemens:simatic_process_historian_2014:*:*:*:*:*:*:*:*
siemens simatic process historian 2019all versionsnvdUScpe:2.3:a:siemens:simatic_process_historian_2019:*:*:*:*:*:*:*:*
siemens simatic process historian 2020all versionsnvdUScpe:2.3:a:siemens:simatic_process_historian_2020:*:*:*:*:*:*:*:*
Siemens SIMATIC Process Historian 2013 and earlier≤ vers:all/*siemens_psirtDE
Siemens SIMATIC Process Historian 2014< SP3 Update 6siemens_psirtDE
Siemens SIMATIC Process Historian 2019≤ vers:all/*siemens_psirtDE
Siemens SIMATIC Process Historian 2020≤ vers:all/*siemens_psirtDE

advisories (2)

Vendor and ecosystem advisories describing this.

SSA-766247SSA-766247: Authentication Vulnerability in SIMATIC Process Historian2021-10-12csaf · siemens_psirtDE
The latest update for SIMATIC Process Historian (PH) fixes an authentication vulnerability in the configuration interface of redundant PH instances that could enable the execution of admin operations on the database. The related vulnerable interface is restricted to local access on recent versions starting from SIMATIC Process Historian 2020. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not, or not yet available.
ICSA-21-287-09Siemens SIMATIC Process Historian2021-10-12icsa · cisa_csaf_otUS
The latest update for SIMATIC Process Historian (PH) fixes an authentication vulnerability in the configuration interface of redundant PH instances that could enable the execution of admin operations on the database. The related vulnerable interface is restricted to local access on recent versions starting from SIMATIC Process Historian 2020. Siemens has released updates for several affected products and recommends to update to the latest versions. 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 2021-10-12modified 2026-06-17

references (7)

External citations — patches, advisories, analysis.

scry

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