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CVE-2021-27395

25
FAUCET Score

CVE-2021-27395 is an authentication bypass vulnerability affecting Siemens SIMATIC Process Historian versions 2013, 2014 (prior to SP3 Update 6), 2019, and 2020. An unauthenticated interface allows a malicious actor to insert, modify, or delete critical data within the software. This vulnerability carries a CVSS score of 8.1 (High), indicating a high-impact threat. It can be exploited remotely over the network with low attack complexity and requires only low privileges, potentially leading to high integrity and availability impacts. Currently, there is no evidence of active exploitation, and no public exploit code (Metasploit, Nuclei, ExploitDB) is available. Community discussion and media coverage for this CVE are minimal.

Impacted Technologies

VendorProductVersion(s)CPE
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:a:siemens:simatic_process_historian_2013:*:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:siemens:simatic_process_historian_2014:-:sp1:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:siemens:simatic_process_historian_2014:-:sp2:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:siemens:simatic_process_historian_2014:-:sp3:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:siemens:simatic_process_historian_2014:-:sp3_update4:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.78%
Probability of exploitation in next 30 days
EPSS Percentile
52.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0078 is in the 45th percentile among its peer group of 17,844 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cert-portal.siemens.com / productcert/pdf/ssa-766247.pdf
Vendor Advisory