CVE-2020-24383
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 FNET through 4.6.4. The code for processing resource records in mDNS queries doesn't check for proper '\0' termination of the resource record name string, leading to an out-of-bounds read, and potentially causing information leak or Denial-or-Service.
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 confidenceFNET through 4.6.4 contains an out-of-bounds read vulnerability in its mDNS query processing code. The function that parses resource record names fails to verify proper null-termination ('\0') of the name string before reading, allowing an attacker to trigger reads beyond buffer boundaries by sending specially crafted mDNS queries. This can leak sensitive memory contents or cause service crashes.
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<= 4.6.4CVSS 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
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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 checksWork through these to decide whether this CVE applies to you.
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Identify FNET library versionSearch for version definitions in FNET source files, typically in fnet.h or fnet_version.h header files. Look for FNET_VERSION, FNET_VER, or similar version constants.Affected if The version is 4.6.4 or earlier (any version through 4.6.4 is affected)
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Confirm mDNS module is in useSearch the project for inclusion of fnet_mdns.h header or references to mDNS functions such as fnet_mdns_init, fnet_mdns_resolve, or FNET_MDNS_ENABLE macro.Affected if mDNS functionality is compiled into or enabled for the application
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Check mDNS service initializationReview application code for calls to fnet_mdns_init() or configuration structures that enable mDNS/zeroconf services. Verify the mDNS responder is registered.Affected if mDNS responder is initialized and active in the firmware/application
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Inspect mDNS name parsing pathIn the FNET source, locate the function that parses resource record names in mDNS queries (typically in fnet_mdns.c or fnet_mdns_resolver.c). Verify whether null-termination checks exist before string operations.Affected if The code lacks explicit null-termination validation before processing name strings in mDNS queries
You are affected if your FNET version is 4.6.4 or earlier AND the mDNS module is enabled and actively processing queries in your application.
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 dataUpdate FNET to version 4.6.5 or later if available; otherwise implement explicit null-termination checks in the mDNS resource record parsing routines and validate name string lengths before processing.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 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 $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-24383 — 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-2020-24383 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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