How severe is CVE-2021-31400?

CVE-2021-31400 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-2021-31400 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31400?

CVE-2021-31400 affects Hcc-embedded Nichestack. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-31400?

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-2021-31400 published?

CVE-2021-31400 was published on 2021-08-19 and last updated on 2026-06-17.

CVE-2021-31400

CVE-2021-31400 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-835.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Hcc-embedded Nichestack
Published: 2021-08-19
Last modified: 2026-06-17

Description

An issue was discovered in tcp_pulloutofband() in tcp_in.c in HCC embedded InterNiche 4.0.1. The TCP out-of-band urgent-data processing function invokes a panic function if the pointer to the end of the out-of-band data points outside of the TCP segment's data. If the panic function hadn't a trap invocation removed, it will enter an infinite loop and therefore cause DoS (continuous loop or a device reset).

Frequently asked questions

What is CVE-2021-31400?: An issue was discovered in tcp_pulloutofband() in tcp_in.c in HCC embedded InterNiche 4.0.1. The TCP out-of-band urgent-data processing function invokes a panic function if the pointer to the end of the out-of-band data points outside of the TCP segment's data. If the panic function hadn't a trap invocation removed, it will enter an infinite loop and therefore cause DoS (continuous loop or a device reset).
How severe is CVE-2021-31400?: CVE-2021-31400 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-2021-31400 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31400?: CVE-2021-31400 affects Hcc-embedded Nichestack. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-31400?: 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-2021-31400 published?: CVE-2021-31400 was published on 2021-08-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:hcc-embedded:nichestack:*:*:*:*:*:*:*:*

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