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NichestackApplication · Hcc Embedded

CVE-2021-31400

HIGH · 7.5 CVSS v3.1 Published 2021-08-19
Fix available
A fix is available. Upgrade to 4.3 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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).

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A denial of service vulnerability exists in the TCP out-of-band (urgent data) processing function tcp_pulloutofband() in HCC embedded InterNiche 4.0.1. When processing urgent data, if the pointer to the end of the OOB data points outside the TCP segment's data boundary, the code invokes a panic handler that enters an infinite loop, causing continuous CPU spin or device reset.

MitigationThe fix requires removing the infinite loop in the panic handler and implementing proper pointer boundary validation in tcp_pulloutofband() to safely handle malformed TCP urgent data; apply vendor patch from HCC if available.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
NichestackApplication
Affected:< 4.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify HCC InterNiche Nichestack installation
    Search your codebase or embedded firmware image for files or libraries containing 'niche', 'niche.stack', or 'InterNiche' references. Check build configuration files, linker scripts, or firmware manifests for the InterNiche TCP/IP stack component.
    Affected if HCC InterNiche Nichestack TCP/IP stack is present in your environment
  2. Determine installed Nichestack version
    Inspect version strings or version defines in Nichestack header files (commonly in include/nipCfg.h, version.h, or similar). Look for NicheStack version constants or the compiled image version information.
    Affected if The discovered version is prior to 4.3 (versions 4.0.1 through 4.2.x are affected)
  3. Locate the vulnerable tcp_pulloutofband function
    Search source code or binary for the function 'tcp_pulloutofband' in TCP processing modules (often in tcp.c, tcpproc.c, or similar). Examine whether this TCP urgent data handling function is present in the build.
    Affected if The tcp_pulloutofband function exists in the deployed code
  4. Verify TCP urgent data processing is in use
    Check application or configuration for usage of TCP urgent data (SO_OOBINLINE socket option, MSG_OOB flag in send/recv calls, or PRU_RCVBUFCOMPATIBLE urgent pointer handling). Review if any network services rely on out-of-band data transmission.
    Affected if TCP out-of-band/urgent data processing is enabled or utilized in your application
  5. Inspect panic handler implementation
    Examine the panic handler code path invoked from tcp_pulloutofband (commonly in panic.c, assert.c, or utility modules). Look for an infinite loop or while(1) construct without proper exit condition in the error path.
    Affected if The panic handler contains an uncontrolled infinite loop that causes CPU spin or device reset

You are affected if HCC InterNiche Nichestack version is below 4.3 and the tcp_pulloutofband function handles TCP urgent data in an environment where OOB data processing is possible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.3 or later
Fixed in 4.3
Interim mitigation

The fix requires removing the infinite loop in the panic handler and implementing proper pointer boundary validation in tcp_pulloutofband() to safely handle malformed TCP urgent data; apply vendor patch from HCC if available.

Recommended fix Moderate confidence

Nichestack 4.3

  1. Identify the current version of HCC embedded InterNiche/Nichestack in use by checking the product documentation or system files
  2. Upgrade the Nichestack library to version 4.3 or later
  3. Verify the upgrade was successful by confirming the new version number
  4. Test the TCP functionality, particularly out-of-band urgent data handling, to ensure proper operation
  5. Monitor the system for any regressions or issues following the upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nichestack Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-31400 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data