How severe is CVE-2021-21279?

CVE-2021-21279 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-21279 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21279?

CVE-2021-21279 affects Contiki-ng. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21279?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-21279 published?

CVE-2021-21279 was published on 2021-06-18 and last updated on 2026-06-17.

CVE-2021-21279

CVE-2021-21279 is a high-severity vulnerability in Contiki-ng with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-835.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 7.8
EPSS exploit prediction: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Contiki-ng
Published: 2021-06-18
Last modified: 2026-06-17

Description

Contiki-NG is an open-source, cross-platform operating system for internet of things devices. In verions prior to 4.6, an attacker can perform a denial-of-service attack by triggering an infinite loop in the processing of IPv6 neighbor solicitation (NS) messages. This type of attack can effectively shut down the operation of the system because of the cooperative scheduling used for the main parts of Contiki-NG and its communication stack. The problem has been patched in Contiki-NG 4.6. Users can apply the patch for this vulnerability out-of-band as a workaround.

Frequently asked questions

What is CVE-2021-21279?: Contiki-NG is an open-source, cross-platform operating system for internet of things devices. In verions prior to 4.6, an attacker can perform a denial-of-service attack by triggering an infinite loop in the processing of IPv6 neighbor solicitation (NS) messages. This type of attack can effectively shut down the operation of the system because of the cooperative scheduling used for the main parts of Contiki-NG and its communication stack. The problem has been patched in Contiki-NG 4.6. Users can apply the patch for this vulnerability out-of-band as a workaround.
How severe is CVE-2021-21279?: CVE-2021-21279 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-21279 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21279?: CVE-2021-21279 affects Contiki-ng. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21279?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-21279 published?: CVE-2021-21279 was published on 2021-06-18 and last updated on 2026-06-17.

References

https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-rr5j-j8m8-fc4f

Affected products (1)

cpe:2.3:o:contiki-ng:contiki-ng:*:*:*:*:*:*:*:*

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