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CVE-2021-31401

23
FAUCET Score

CVE-2021-31401 is a high-severity vulnerability affecting HCC embedded InterNiche 4.0.1 and various Siemens products utilizing the NicheStack TCP/IP stack. It stems from improper sanitization of the IP total length field, leading to an integer overflow when calculating IP data length with a crafted IP packet. This network-exploitable vulnerability requires no user interaction and can result in a complete loss of availability (CVSS 7.5, Attack Complexity Low). While not currently listed in CISA's KEV catalog or having public exploit code (Metasploit, Nuclei, ExploitDB), it has garnered some community discussion and media coverage, indicating awareness within the cybersecurity community.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.3CPE matchmatch criteria
cpe:2.3:a:hcc-embedded:nichestack:*:*:*:*:*:*:*:*
< 1.2.0CPE matchmatch criteria
cpe:2.3:o:siemens:sentron_3wl_com35_firmware:*:*:*:*:*:*:*:*
< 2.0.0CPE matchmatch criteria
cpe:2.3:o:siemens:sentron_3wa_com190_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.25%
Probability of exploitation in next 30 days
EPSS Percentile
81.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0225 is in the 66th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

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-789208.pdf
MitigationThird Party Advisory
forescout.com / blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack
MitigationThird Party Advisory
kb.cert.org / vuls/id/608209
Third Party AdvisoryUS Government Resource