CVE-2021-27697
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 · uneditedRIOT-OS 2021.01 contains a buffer overflow vulnerability in sys/net/gnrc/routing/rpl/gnrc_rpl_validation.c through the gnrc_rpl_validation_options() function.
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 confidenceA buffer overflow vulnerability exists in RIOT-OS 2021.01 within the gnrc_rpl_validation_options() function in the RPL (Routing Protocol for Low-Power and Lossy Networks) validation code. This flaw in sys/net/gnrc/routing/rpl/gnrc_rpl_validation.c allows remote attackers to potentially execute arbitrary code or cause denial of service via specially crafted RPL messages.
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= 2021.01CVSS 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 the RIOT-OS versionCheck the firmware version or build identifier on the device. On Linux systems with RIOT tools, run: 'riot-version' or inspect the firmware metadata. If you built the image yourself, check the git tag or version file used at build time.Affected if The running firmware is exactly version 2021.01 or was built from that release tag.
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Verify RPL module is enabledInspect the application's Makefile or board configuration for 'USEMODULE += gnrc_rpl' or check if 'RPL' appears in the module list. In the built firmware, check for symbols related to RPL using 'nm firmware.elf | grep -i rpl' or equivalent.Affected if The gnrc_rpl module is included in the build.
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Confirm gnrc_rpl_validation.c is presentExamine the firmware image or source tree for the file sys/net/gnrc/routing/rpl/gnrc_rpl_validation.c. Use 'find . -name gnrc_rpl_validation.c' in the source tree or check firmware contents for the string 'gnrc_rpl_validation_options'.Affected if The vulnerable validation file exists in the compiled firmware.
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Check if RPL is actively configuredInspect the network configuration or runtime settings on the device. Look for RPL instance IDs, DODAG configurations, or RPL-related runtime parameters. On the device shell (if available), run commands that list active network protocols or RPL status.Affected if RPL routing is actively configured or running on the device.
A device is affected if it runs RIOT-OS 2021.01 with the gnrc_rpl module enabled and RPL validation code present in the firmware, exposing it to specially crafted RPL packets.
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 to a patched version of RIOT-OS when available. If no patch exists, implement network-level filtering to reject malformed RPL packets at border routers or gateways.
- Consultation6.0 h
- Implementation12.0 h
- Testing10.0 h
- Review / QA6.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $9,504.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-27697 — 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-2021-27697 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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