CVE-2020-14936
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 · uneditedBuffer overflows were discovered in Contiki-NG 4.4 through 4.5, in the SNMP agent. Functions parsing the OIDs in SNMP requests lack sufficient allocated target-buffer capacity verification when writing parsed OID values. The function snmp_oid_decode_oid() may overwrite memory areas beyond the provided target buffer, when called from snmp_message_decode() upon an SNMP request reception. Because the content of the write operations is externally provided in the SNMP requests, it enables a remote overwrite of an IoT device's memory regions beyond the allocated buffer. This overflow may allow remote overwrite of stack and statically allocated variables memory regions by sending a crafted SNMP request.
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 confidenceBuffer overflow in Contiki-NG 4.4-4.5 SNMP agent allows remote attackers to overwrite memory beyond allocated buffers via crafted SNMP requests with oversized OIDs. The snmp_oid_decode_oid() function called from snmp_message_decode() lacks bounds checking when writing parsed OID values, enabling potential remote code execution or denial of service by overwriting stack and static variables.
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>= 4.4, <= 4.5CVSS 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 Contiki-NG deploymentDetermine if your IoT/embedded device or project uses the Contiki-NG operating system. Check firmware build scripts, SDK documentation, or device specifications for references to Contiki-NG.Affected if Contiki-NG is not in use - this CVE only applies to Contiki-NG environments
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Check Contiki-NG versionLocate the Contiki-NG version in your build system, firmware metadata, or source tree. Look for version.h, release tags, or build configuration files that specify the Contiki-NG version.Affected if Installed version falls within 4.4 through 4.5 inclusive
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Verify SNMP agent is enabledExamine your Contiki-NG configuration files (such as project-conf.h or Makefile) for SNMP-related defines. Look for SNMP_CONF_ENABLED, SNMP_AGENT, or similar configuration flags that enable the SNMP stack.Affected if SNMP agent is not compiled or enabled in the build configuration
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Inspect SNMP OID decoding codeReview the snmp_oid_decode_oid() function in your Contiki-NG SNMP implementation source. Check whether bounds checking or buffer capacity validation exists before writing parsed OID values to memory.Affected if The function lacks explicit bounds checking and the code is from an affected Contiki-NG version
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Check SNMP exposureReview network configuration to determine if SNMP service is accessible from untrusted networks. Check firewall rules, ACLs, or network segmentation around devices running Contiki-NG.Affected if SNMP service is exposed to external or untrusted network segments without access controls
A defender is affected if their device runs Contiki-NG versions 4.4-4.5 with the SNMP agent enabled and the snmp_oid_decode_oid() function lacks buffer bounds validation.
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 dataUpgrade Contiki-NG to version beyond 4.5 when available, or implement explicit buffer capacity validation in snmp_oid_decode_oid() and snmp_message_decode() functions. Deploy network-level SNMP access controls (ACLs/firewall rules) to limit SNMP exposure until patched.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-14936 — 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-2020-14936 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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- Version or environment caveats, and links to real fixes
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