CVE-2020-17468
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 the hop-by-hop header (in the IPv6 extension headers) doesn't check for a valid length of an extension header, and therefore an out-of-bounds read can occur in _fnet_ip6_ext_header_handler_options in fnet_ip6.c, leading to 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 confidenceAn out-of-bounds read vulnerability exists in FNET through 4.6.4 in the IPv6 hop-by-hop extension header processing function _fnet_ip6_ext_header_handler_options in fnet_ip6.c. The code fails to validate the extension header length before processing, allowing specially crafted IPv6 packets with malformed extension headers to trigger the out-of-bounds read and cause 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 your codebase, dependencies, or firmware image for the string 'FNET' or files named 'fnet*.c' / 'fnet*.h'. Check build files, linker scripts, or dependency manifests for references to FNET.Affected if FNET library or its components are found in your environment
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Determine installed FNET versionLocate the version definition in FNET source files, typically in a header file like fnet_version.h or in the main fnet.c file. Look for version constants such as FNET_VERSION, FNET_RELEASE_VERSION, or version macros.Affected if The version is 4.6.4 or lower, or the version cannot be determined (older/unversioned release)
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Verify IPv6 protocol support is enabledCheck your configuration files, build settings, or feature flags for IPv6 enablement. Look for symbols like FNET_CFG_IP6, FNET_IP6, or similar configuration macros. Search for compilation flags that enable IPv6 functionality.Affected if IPv6 support is compiled in or enabled in the runtime configuration
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Inspect the vulnerable functionSearch the FNET source code for the function '_fnet_ip6_ext_header_handler_options' in fnet_ip6.c. Verify whether it lacks proper length validation before processing extension headers. Look for the presence of length checks before accessing extension header fields.Affected if The function exists and processes IPv6 extension headers without validating the extension header length field first
You are affected if FNET version 4.6.4 or lower is in use, IPv6 is enabled, and the vulnerable _fnet_ip6_ext_header_handler_options function processes extension headers without validating their length.
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 includes proper extension header length validation, or add explicit length checks before processing IPv6 extension headers in the vulnerable function.
- Consultation2.0 h
- Implementation4.0 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 $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-17468 — 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-2020-17468 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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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.
- 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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