How severe is CVE-2021-31228?

CVE-2021-31228 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 high, and availability none.

Is CVE-2021-31228 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31228?

CVE-2021-31228 affects Hcc-embedded Nichestack. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-31228?

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-2021-31228 published?

CVE-2021-31228 was published on 2021-08-19 and last updated on 2026-06-17.

CVE-2021-31228

CVE-2021-31228 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-330.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (66th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-330
Affected product: Hcc-embedded Nichestack
Published: 2021-08-19
Last modified: 2026-06-17

Description

An issue was discovered in HCC embedded InterNiche 4.0.1. This vulnerability allows the attacker to predict a DNS query's source port in order to send forged DNS response packets that will be accepted as valid answers to the DNS client's requests (without sniffing the specific request). Data is predictable because it is based on the time of day, and has too few bits.

Frequently asked questions

What is CVE-2021-31228?: An issue was discovered in HCC embedded InterNiche 4.0.1. This vulnerability allows the attacker to predict a DNS query's source port in order to send forged DNS response packets that will be accepted as valid answers to the DNS client's requests (without sniffing the specific request). Data is predictable because it is based on the time of day, and has too few bits.
How severe is CVE-2021-31228?: CVE-2021-31228 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 high, and availability none.
Is CVE-2021-31228 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31228?: CVE-2021-31228 affects Hcc-embedded Nichestack. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-31228?: 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-2021-31228 published?: CVE-2021-31228 was published on 2021-08-19 and last updated on 2026-06-17.

References

Affected products (1)

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

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-2020-35683 — High (CVSS 7.5): An issue was discovered in HCC Nichestack 3.0. The code that parses ICMP packets relies on an unchecked value of the IP…

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