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Nichestack Ipv4Application · Hcc Embedded

CVE-2020-25767

HIGH · 7.5 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 →
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 HCC Embedded NicheStack IPv4 4.1. The dnc_copy_in routine for parsing DNS domain names does not check whether a domain name compression pointer is pointing within the bounds of the packet (e.g., forward compression pointer jumps are allowed), which leads to an Out-of-bounds Read, and a Denial-of-Service as a consequence.

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

In HCC Embedded NicheStack IPv4 4.1, the dnc_copy_in function that parses DNS domain names fails to validate that compression pointers remain within the packet boundaries. Specifically, the function allows forward compression pointer jumps without checking if the pointer target is within the packet, leading to an out-of-bounds memory read. This can cause the stack to read beyond the DNS packet data, resulting in a denial-of-service condition.

MitigationImplement bounds checking on all DNS compression pointers in dnc_copy_in to ensure they reference locations within the packet boundaries before dereferencing, and reject or truncate any pointer that would read outside the packet buffer.

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 Ipv4Application
Affected:= 4.1

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
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 the installed NicheStack version
    Check the version string in the firmware, library headers, or build documentation for HCC Embedded NicheStack IPv4. Look for version 4.1 specifically.
    Affected if The installed version is exactly 4.1 (not a later patched version)
  2. Verify DNS client/resolver is enabled
    Inspect the project configuration files or compile-time definitions (such as defines like DNS_CLIENT_ENABLED, NS_DNS, or similar) to determine if the DNS resolver module is compiled into the image.
    Affected if DNS client functionality is enabled and the firmware processes DNS responses
  3. Check for DNS packet processing code
    Search the firmware image or source code for the function name 'dnc_copy_in' or references to DNS name compression handling in the network stack.
    Affected if The dnc_copy_in function exists in the firmware and handles incoming DNS packets
  4. Inspect memory configuration for network buffers
    Examine the network buffer sizes and DNS packet buffer allocations in the configuration. Look for the DNS packet buffer size setting (often defined as DNS_MAX_PACKET_SIZE or similar).
    Affected if DNS packet buffers are configured without bounds-checking validation on compression pointers

A system is affected if it runs HCC Embedded NicheStack IPv4 version 4.1 with the DNS client enabled and processes incoming DNS responses using the vulnerable dnc_copy_in function.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement bounds checking on all DNS compression pointers in dnc_copy_in to ensure they reference locations within the packet boundaries before dereferencing, and reject or truncate any pointer that would read outside the packet buffer.

Recommended fix Moderate confidence

Obtain the fixed release from HCC Embedded - contact vendor for specific version number

  1. Contact HCC Embedded to obtain the patched version of NicheStack IPv4 that addresses CVE-2020-25767
  2. Request the specific security update or hotfix for the dnc_copy_in routine that validates DNS compression pointer bounds
  3. Apply the vendor-provided patch or update to your NicheStack implementation
  4. After patching, verify the fix by testing DNS response parsing with crafted packets containing forward compression pointers
  5. Confirm the update does not introduce regressions in DNS resolution functionality
Caveat Test thoroughly in your specific embedded environment as NicheStack is often used in critical infrastructure devices; regression testing recommended

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

Fix this in Nichestack Ipv4 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
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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-2020-25767 in production — separate from our analysis above.

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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
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