CVSS 3.1
9.1 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NCVE-2020-35685
Critical (9.1). EPSS 2.1% chance of exploitation in the next 30 days.
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.)
Severity
- EPSS
- 2.1% chance of exploitation in the next 30 days; higher than 81% of CVEs (scores of 2026-10-31)
- CWE
- CWE-330
- Published
- Modified
- Record from
- the NVD, synced
Affected
- hcc-embedded:nichestack
- siemens:sentron_3wa_com190_firmware
- siemens:sentron_3wl_com35_firmware