How severe is CVE-2021-31401?

CVE-2021-31401 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-2021-31401 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-2021-31401?

CVE-2021-31401 primarily affects Hcc-embedded Nichestack. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-31401?

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-2021-31401 published?

CVE-2021-31401 was published on 2021-08-19 and last updated on 2026-06-17.

CVE-2021-31401

CVE-2021-31401 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-20.

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-20
Affected product: Hcc-embedded Nichestack
Published: 2021-08-19
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-31401?: 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.
How severe is CVE-2021-31401?: CVE-2021-31401 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-2021-31401 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-2021-31401?: CVE-2021-31401 primarily affects Hcc-embedded Nichestack. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-31401?: 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-2021-31401 published?: CVE-2021-31401 was published on 2021-08-19 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:hcc-embedded:nichestack:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sentron_3wl_com35_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sentron_3wa_com190_firmware:*:*:*:*:*:*:*:*

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