CVE-2020-25107
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 · uneditedAn issue was discovered in the DNS implementation in Ethernut in Nut/OS 5.1. There is no check on whether a domain name has '\0' termination. This may lead to successful Denial-of-Service, and possibly Remote Code Execution.
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 · moderate confidenceThe DNS implementation in Ethernut/Nut/OS 5.1 lacks validation to check whether domain names are properly null-terminated ('\0'). Without this check, the DNS parser may mishandle domain name buffers, leading to buffer overruns that can cause denial of service and potentially remote code execution.
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<= 5.1CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify Nut/OS versionLocate the Nut/OS installation or firmware and determine the version number (typically found in build files, headers, or firmware metadata). Compare the version to 5.1 or lower.Affected if The installed version is Nut/OS 5.1 or any version lower than 5.1.
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Verify DNS client functionality is enabledCheck the Nut/OS configuration files (such as nutconf, defbuild.h, or custom config headers) for DNS-related settings like NUTDEBUG, DNS_ENABLE, or similar DNS feature flags.Affected if DNS client support is compiled into the firmware or application.
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Identify DNS domain name parsing codeLocate the DNS parsing routines in the codebase, typically in files related to dns.c, resolver.c, or network packet handling within the Nut/OS source tree. Look for functions that parse domain names from DNS response packets.Affected if Custom or vendor-modified DNS parsing code exists that handles domain name buffers without explicit null-termination validation.
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Inspect domain name buffer handlingExamine the DNS domain name parsing routine for missing checks for the null terminator ('\0') before processing domain name buffers. Search for memcpy, strcpy, or similar operations on domain name fields without prior validation.Affected if The code processes domain name buffers from DNS responses without verifying they end with a null byte first.
You are affected if you are running any version of Ethernut/Nut/OS 5.1 or lower with the DNS client functionality enabled, and your DNS parsing implementation lacks null-termination validation before processing domain name buffers.
Generated from the published advisory. Verify against your own configuration.
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 dataImplement a null-termination check in the DNS domain name parsing routine to validate that domain names end with '\0' before processing, and update to a patched version of Nut/OS if available.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-25107 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-25107 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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