How severe is CVE-2020-35683?

CVE-2020-35683 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-35683 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-35683?

CVE-2020-35683 primarily affects Hcc-embedded Nichestack. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-35683?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-35683 published?

CVE-2020-35683 was published on 2021-08-19 and last updated on 2026-06-17.

CVE-2020-35683

CVE-2020-35683 is a high-severity vulnerability in Hcc-embedded Nichestack with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (81st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Hcc-embedded Nichestack
Published: 2021-08-19
Last modified: 2026-06-17

Description

An issue was discovered in HCC Nichestack 3.0. The code that parses ICMP packets relies on an unchecked value of the IP payload size (extracted from the IP header) to compute the ICMP checksum. When the IP payload size is set to be smaller than the size of the IP header, the ICMP checksum computation function may read out of bounds, causing a Denial-of-Service.

Frequently asked questions

What is CVE-2020-35683?: An issue was discovered in HCC Nichestack 3.0. The code that parses ICMP packets relies on an unchecked value of the IP payload size (extracted from the IP header) to compute the ICMP checksum. When the IP payload size is set to be smaller than the size of the IP header, the ICMP checksum computation function may read out of bounds, causing a Denial-of-Service.
How severe is CVE-2020-35683?: CVE-2020-35683 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-35683 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-35683?: CVE-2020-35683 primarily affects Hcc-embedded Nichestack. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-35683?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-35683 published?: CVE-2020-35683 was published on 2021-08-19 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:hcc-embedded:nichestack:3.0:*:*:*:*:*:*:*
cpe:2.3:o:siemens:7km9300-0ae02-0aa0_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Hcc-embedded Nichestack

CVE-2020-35685 — Critical (CVSS 9.1): An issue was discovered in HCC Nichestack 3.0. The code that generates Initial Sequence Numbers (ISNs) for TCP…
CVE-2021-36762 — High (CVSS 7.5): An issue was discovered in HCC Embedded InterNiche NicheStack through 4.3. The tfshnd():tftpsrv.c TFTP packet…
CVE-2021-31401 — High (CVSS 7.5): An issue was discovered in tcp_rcv() in nptcp.c in HCC embedded InterNiche 4.0.1. The TCP header processing code…
CVE-2021-27565 — High (CVSS 7.5): The web server in InterNiche NicheStack through 4.0.1 allows remote attackers to cause a denial of service (infinite…
CVE-2020-35684 — High (CVSS 7.5): An issue was discovered in HCC Nichestack 3.0. The code that parses TCP packets relies on an unchecked value of the IP…
CVE-2021-31400 — High (CVSS 7.5): An issue was discovered in tcp_pulloutofband() in tcp_in.c in HCC embedded InterNiche 4.0.1. The TCP out-of-band…

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Other CWE-125 (Out-of-bounds Read) vulnerabilities

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CVE-2021-41556 — Critical (CVSS 10.0): sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that…
CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
CVE-2013-0767 — Critical (CVSS 10.0): The nsSVGPathElement::GetPathLengthScale function in Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and…

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