Skip to content
Fencer Intel
critical 9.1

CVE-2020-35685 json

An issue was discovered in HCC Nichestack 3.0.

published 5y ago modified 4mo ago also EUVD-2020-23344

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

An issue was discovered in HCC Nichestack 3.0. The code that generates Initial Sequence Numbers (ISNs) for TCP connections derives the ISN from an insufficiently random source. As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones. (Proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.)

Patch / fix

  • siemens sentron_3wa_com190_firmware 2.0.0
  • siemens sentron_3wl_com35_firmware 1.2.0

Is CVE-2020-35685 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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

2.05% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:P/A:N

Classification

Weakness
  • CWE-330 Use of Insufficiently Random Values

References

Sources

Fencer Intel 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.