CVE-2020-17469
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 IPv6 fragment reassembly tries to access a previous fragment starting from a network incoming fragment that still doesn't have a reference to the previous one (which supposedly resides in the reassembly list). When faced with an incoming fragment that belongs to a non-empty fragment list, IPv6 reassembly must check that there are no empty holes between the fragments: this leads to an uninitialized pointer dereference in _fnet_ip6_reassembly in fnet_ip6.c, and causes Denial-of-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 · high confidenceFNET through 4.6.4 has an uninitialized pointer dereference vulnerability in IPv6 fragment reassembly (_fnet_ip6_reassembly in fnet_ip6.c). When processing an incoming IPv6 fragment that belongs to an existing fragment list, the code attempts to access a previous fragment reference that has not yet been properly initialized or linked, leading to a NULL/uninitialized pointer dereference and resulting in denial of service.
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
- 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 checksWork through these to decide whether this CVE applies to you.
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Identify FNET library presenceSearch for FNET source files or headers in the project (look for fnet.h, fnet_ip6.c, or references to FNET in build artifacts)Affected if FNET library is present in the environment
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Determine FNET versionCheck for version information in FNET header files (commonly fnet.h defines FNET_VERSION) or in any version documentation/config filesAffected if Installed version is 4.6.4 or earlier (any version through 4.6.4)
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Verify IPv6 support is enabledInspect build configuration or compile-time flags for FNET_IP6_SUPPORT or similar IPv6 configuration optionsAffected if IPv6 support is enabled in the FNET configuration
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Confirm IPv6 fragment processing is activeCheck if the system processes incoming IPv6 traffic by reviewing network configuration or code that enables IP6 reassembly (_fnet_ip6_reassembly function is called)Affected if IPv6 fragment reassembly functionality is in use
The environment is affected if FNET version 4.6.4 or earlier is in use AND IPv6 support with fragment reassembly is enabled, as the uninitialized pointer dereference occurs during IPv6 fragment processing.
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 a version beyond 4.6.4 that addresses the IPv6 fragment reassembly pointer validation issue, or apply a patch that ensures proper initialization and validation of fragment references before dereferencing in the reassembly logic.
- Consultation3.0 h
- Implementation6.0 h
- Testing5.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,752.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-17469 — 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-2020-17469 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
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