dbcve.org
Nichestack Tcp\/ipApplication · Hcc Embedded

CVE-2020-25928

CRITICAL · 9.8 CVSS v3.1 Published 2021-08-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
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
The DNS feature in InterNiche NicheStack TCP/IP 4.0.1 is affected by: Buffer Overflow. The impact is: execute arbitrary code (remote). The component is: DNS response processing functions: dns_upcall(), getoffset(), dnc_set_answer(). The attack vector is: a specific DNS response packet. The code does not check the "response data length" field of individual DNS answers, which may cause out-of-bounds read/write operations, leading to Information leak, Denial-or-Service, or Remote Code Execution, depending on the context.

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

Buffer overflow vulnerability in NicheStack TCP/IP 4.0.1 DNS response processing. The functions dns_upcall(), getoffset(), and dnc_set_answer() fail to validate the 'response data length' field in DNS answer records, allowing crafted DNS responses to trigger out-of-bounds read/write operations. This can lead to information disclosure, denial of service, or remote code execution.

MitigationUpdate to a patched version of NicheStack if available. Until a patch is released, implement network-level controls to restrict DNS traffic to trusted sources, or disable DNS if not required. Consider DNS response validation/proxy services at the network boundary.

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
Nichestack Tcp\/ipApplication
Affected:= 4.0.1

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 if NicheStack TCP/IP stack is in use
    Review system documentation, firmware metadata, or software BOM (bill of materials) to identify the TCP/IP stack implementation. NicheStack is an embedded stack often used by industrial control system vendors. Look for references to 'Hcc Embedded' or 'NicheStack' in product specifications or firmware strings.
    Affected if The system uses NicheStack from Hcc Embedded as its TCP/IP stack implementation.
  2. Determine the installed NicheStack version
    Locate the version string in the firmware image, library files, or product firmware release notes. The affected version is specifically 4.0.1. Check firmware metadata, embedded string literals, or contact the equipment vendor for version confirmation.
    Affected if The installed NicheStack version is exactly 4.0.1.
  3. Verify DNS client or server functionality is enabled
    Review the system or application configuration to determine if DNS resolution or DNS response handling is enabled. Check for DNS-related configuration parameters, DNS server settings, or DNS-upcall handlers in the network configuration. Look for references to dns_upcall(), getoffset(), or dnc_set_answer() in the codebase if source code is available.
    Affected if DNS functionality that processes response data is enabled and actively used.
  4. Assess network exposure to untrusted DNS responses
    Examine network architecture and firewall rules to determine if the device accepts DNS responses from untrusted or external sources. Determine if DNS traffic is restricted to known-trusted DNS servers or if the device processes DNS responses from arbitrary network sources.
    Affected if The device processes DNS responses from untrusted or non-local network sources without additional validation.

A system is affected if it runs NicheStack TCP/IP version 4.0.1 with DNS functionality enabled and exposed to untrusted DNS response traffic.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update to a patched version of NicheStack if available. Until a patch is released, implement network-level controls to restrict DNS traffic to trusted sources, or disable DNS if not required. Consider DNS response validation/proxy services at the network boundary.

Fix this in Nichestack Tcp\/ip Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA3.0 h
16.0 hours of engineering $2,820
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,512.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2020-25928 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2020-25928 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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