How severe is CVE-2021-21281?

CVE-2021-21281 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.

Is CVE-2021-21281 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21281?

CVE-2021-21281 affects Contiki-ng. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21281?

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-2021-21281 published?

CVE-2021-21281 was published on 2021-06-18 and last updated on 2026-06-17.

CVE-2021-21281

CVE-2021-21281 is a high-severity vulnerability in Contiki-ng with a CVSS 3.x base score of 7.0. 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-120.

Key facts

Severity: High (CVSS 3.x base score 7.0)
CVSS v2: 7.5
EPSS exploit prediction: 1% (56th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
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. A buffer overflow vulnerability exists in Contiki-NG versions prior to 4.6. After establishing a TCP socket using the tcp-socket library, it is possible for the remote end to send a packet with a data offset that is unvalidated. 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-2021-21281?: Contiki-NG is an open-source, cross-platform operating system for internet of things devices. A buffer overflow vulnerability exists in Contiki-NG versions prior to 4.6. After establishing a TCP socket using the tcp-socket library, it is possible for the remote end to send a packet with a data offset that is unvalidated. 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-2021-21281?: CVE-2021-21281 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.
Is CVE-2021-21281 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21281?: CVE-2021-21281 affects Contiki-ng. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21281?: 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-2021-21281 published?: CVE-2021-21281 was published on 2021-06-18 and last updated on 2026-06-17.

References

Affected products (1)

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

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