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Fencer Vulns
high 7.5

CVE-2021-31401 json

An issue was discovered in tcp_rcv() in nptcp.c in HCC embedded InterNiche 4.0.1.

published 2021-08-19 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-18311

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.3%
EPSS 2.3% chance of exploitation in 30 days, percentile 83%
public exploits
0
none known

Summary

An issue was discovered in tcp_rcv() in nptcp.c in HCC embedded InterNiche 4.0.1. The TCP header processing code doesn't sanitize the value of the IP total length field (header length + data length). With a crafted IP packet, an integer overflow occurs whenever the value of the IP data length is calculated by subtracting the length of the header from the total length of the IP packet.

Patch / fix

  • hcc-embedded nichestack 4.3
  • siemens sentron_3wl_com35_firmware 1.2.0
  • siemens sentron_3wa_com190_firmware 2.0.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-21-217-01 updated cvss 7.5

HCC Embedded InterNiche TCP/IP stack, NicheLite (Update B)

  • HCC Embedded InterNiche stack < 4.3 HCC Embedded NicheLite < 4.3
    affected: vendor fix mitsubishielectric.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

Exploit prediction

2.25% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.