CVE-2021-31226: An issue was discovered in HCC embedded InterNiche 4.0.1

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2021-31226 is a critical-severity flaw (CVSS 9.8) affecting interniche. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in HCC embedded InterNiche 4.0.1. A potential heap buffer overflow exists in the code that parses the HTTP POST request, due to lack of size validation. This vulnerability requires the attacker to send a crafted HTTP POST request with a URI longer than 50 bytes. This leads to a heap overflow in wbs_post() via an strcpy() call.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.2% (top 12%)
CISA exploited list	No
Weakness	CWE-787
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 interniche DOWNGRADE

Affected: 4.0.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.0.1 (Debian / Ubuntu)

apt-cache madison interniche sudo apt install interniche=<VERSION_BEFORE_4.0.1> sudo apt-mark hold interniche

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list interniche sudo dnf downgrade interniche-<VERSION_BEFORE_4.0.1> sudo dnf versionlock add interniche

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2021-31226?

interniche: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-31226 being exploited?

CVE-2021-31226 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-2021-31226 affect?

CVE-2021-31226 affects interniche. Severity is critical (CVSS 9.8). An issue was discovered in HCC embedded InterNiche 4.0.1. A potential heap buffer overflow exists in the code that parses the HTTP POST request, due to lack of size validation. This vulnerability requires the attacker to send a crafted HTTP

How urgent is CVE-2021-31226?

Priority 61/100. Critical severity; Remotely exploitable, no login, no user action

References

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