What’s Vulnerable › Vulnerabilities

CVE-2021-21410: Out-of-bounds read in the 6LoWPAN implementation

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-18 · updated 2026-06-17
• Weakness: CWE-125

Description

Contiki-NG is an open-source, cross-platform operating system for Next-Generation IoT devices. An out-of-bounds read can be triggered by 6LoWPAN packets sent to devices running Contiki-NG 4.6 and prior. The IPv6 header decompression function (<code>uncompress_hdr_iphc</code>) does not perform proper boundary checks when reading from the packet buffer. Hence, it is possible to construct a compressed 6LoWPAN packet that will read more bytes than what is available from the packet buffer. As of time of publication, there is not a release with a patch available. Users can apply the patch for this vulnerability out-of-band as a workaround.

Affected products

• contiki-ng: through 4.6

References

• https://github.com/contiki-ng/contiki-ng/pull/1482
• https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-hhwj-2p59-v8p9
• https://github.com/contiki-ng/contiki-ng/pull/1482
• https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-hhwj-2p59-v8p9

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