Security readout for executives and security teams
Plain-English summary
CVE-2021-21280 is a memory corruption flaw in Contiki-NG, an operating system used for IoT devices. Versions before 4.6 can write outside a buffer while handling 6LoWPAN extension headers. The main business risk is disruption of embedded or sensor networks that depend on affected firmware.
Executive priority
Treat this as high priority for environments running Contiki-NG-based IoT devices, especially operational networks where device availability matters. Prioritize inventory first, because downstream affected products are not named in the sources.
Technical view
Affected Contiki-NG versions before 4.6 can perform an out-of-bounds write when transmitting a 6LoWPAN packet containing a chain of extension headers. The advisory maps this to CWE-787 and CVSS 3.1 score 8.6, with network attack vector, low complexity, no privileges, no user interaction, and high availability impact.
Likely exposure
Exposure is most likely in IoT, embedded, or sensor-network deployments that use Contiki-NG before 4.6 and include 6LoWPAN networking. The sources do not identify downstream device vendors, specific products, or managed service platforms.
Exploitation context
The provided sources do not report active exploitation, and the CVE is not listed as KEV in the bundle. The CVSS vector indicates network reachability and no authentication requirement, but the sources do not provide exploit maturity or real-world attack evidence.
Researcher notes
Focus validation on Contiki-NG version, 6LoWPAN use, and whether the upstream fix from PR 1409 is present. Evidence supports patched status in Contiki-NG 4.6, but does not establish exploitation in the wild or downstream product impact.
Mitigation direction
- Upgrade affected Contiki-NG deployments to version 4.6 or later.
- Apply the upstream patch out-of-band where full upgrade is not immediately possible.
- Check device or firmware vendor guidance for Contiki-NG dependency updates.
- Confirm rebuilt firmware includes the patched 6LoWPAN handling code.
Validation and detection
- Inventory firmware and SBOMs for Contiki-NG versions earlier than 4.6.
- Confirm whether deployed devices use Contiki-NG 6LoWPAN networking.
- Review vendor advisories for downstream firmware exposure and update availability.
- Verify deployed firmware versions after remediation.
- Document unsupported affected devices for replacement or compensating controls.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-21280 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H3.94.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-r768-hrhf-v592CVE reference · x_refsource_CONFIRM
- https://github.com/contiki-ng/contiki-ng/pull/1409CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.