CVE-2021-31400: An issue was discovered in tcp_pulloutofband() in tcp_in.c in HCC embedded InterNiche 4.0.1

Q: How do I fix CVE-2021-31400?

nichestack: upgrade to 4.3. Exact commands for each OS are on this page.

Q: Is CVE-2021-31400 being exploited?

CVE-2021-31400 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-31400 affect?

CVE-2021-31400 affects nichestack. Severity is 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 urgent-data processing function invokes a panic function if the pointer to the end of the out-of-band data points outside of th

Q: How urgent is CVE-2021-31400?

Priority 50/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2021-31400 is a high-severity flaw (CVSS 7.5) affecting nichestack. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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).

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 26%)
CISA exploited list	No
Weakness	CWE-835
Published	2021-08-19
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: hcc-embedded

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-08-19 11:15 UTCPublished CVE record published
2026-06-17 03:51 UTCUpdated Record last modified

hcc-embedded nichestack UPGRADE

Affected: < 4.3

Fixed in: 4.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nichestack || rpm -q nichestack || nichestack --version

2. UPGRADE to 4.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nichestack

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nichestack

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-31400?

nichestack: upgrade to 4.3. Exact commands for each OS are on this page.

Is CVE-2021-31400 being exploited?

CVE-2021-31400 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-31400 affect?

CVE-2021-31400 affects nichestack. Severity is 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 urgent-data processing function invokes a panic function if the pointer to the end of the out-of-band data points outside of th

How urgent is CVE-2021-31400?

Priority 50/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-36762 HIGH 7.5 UPGRADE An issue was discovered in HCC Embedded InterNiche NicheStack through 4.3
CVE-2021-31401 HIGH 7.5 UPGRADE UPGRADE An issue was discovered in tcp_rcv() in nptcp.c in HCC embedded InterNiche 4.0.1
CVE-2021-31228 HIGH 7.5 UPGRADE An issue was discovered in HCC embedded InterNiche 4.0.1
CVE-2021-31227 HIGH 7.5 UPGRADE An issue was discovered in HCC embedded InterNiche 4.0.1
CVE-2021-27565 HIGH 7.5 UPGRADE The web server in InterNiche NicheStack through 4.0.1 allows remote attackers to cause a denial of service (in

References

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