CVE-2021-36762
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 HCC Embedded InterNiche NicheStack through 4.3. The tfshnd():tftpsrv.c TFTP packet processing function doesn't ensure that a filename is adequately '\0' terminated; therefore, a subsequent call to strlen for the filename might read out of bounds of the protocol packet buffer (if no '\0' byte exists within a reasonable range).
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 confidenceIn HCC Embedded InterNiche NicheStack TFTP server, the tfshnd() function in tftpsrv.c processes filenames from TFTP packets without verifying null-termination. When strlen() is subsequently called on the filename pointer, it can read beyond the packet buffer boundaries if no terminating null byte exists within the packet, causing an out-of-bounds read vulnerability.
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< 4.3CVSS 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
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
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.
-
Confirm NicheStack TFTP server is in useIdentify if the system runs HCC Embedded NicheStack with TFTP server functionality enabled. Check application code or system documentation for inclusion of tftpsrv.c or calls to TFTP-related functions.Affected if TFTP server component is present and active in the environment
-
Check NicheStack versionLocate the NicheStack library or header files in the deployment. Common locations: embedded firmware images, SDK installations, or source code repositories. Look for version definition in niche.h or similar version header files.Affected if The installed version is earlier than 4.3 (any version below 4.3)
-
Inspect tfshnd function implementationReview tftpsrv.c source code for the tfshnd() function. Search for the filename handling section where the packet buffer is processed. Verify whether null-termination validation exists before the strlen() call.Affected if The tfshnd() function does not contain explicit null-termination checks on the filename buffer prior to calling strlen()
The environment is affected if it runs HCC Embedded NicheStack versions prior to 4.3 with the TFTP server (tfshnd function) enabled, and the source code lacks null-termination validation on the filename field before strlen is invoked.
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.
dbcve · scoped4.3
Add explicit null-termination validation for the filename field in tfshnd() before calling strlen, ensuring the filename is bounded within the TFTP packet buffer.
NicheStack 4.3.1 or later fixed release
- Contact HCC Embedded (www.hcc-embedded.com) to obtain the fixed release of NicheStack version 4.3.1 or later
- Verify the exact version deployed in your product by reviewing your software bill of materials (SBOM)
- Apply the updated NicheStack library to your build system, ensuring all components are rebuilt
- If using a third-party integration of NicheStack (e.g., through an RTOS or hardware vendor), confirm they have incorporated the fix or obtain a patched version from them
- Regression test TFTP functionality to ensure the fix does not introduce regressions
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation2.0 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 $3,392.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-36762 — 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-2021-36762 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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
- No spam, self-promotion, credentials, or personal data