Is CVE-2021-21280 in the CISA KEV catalog?

No. CVE-2021-21280 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-21280?

CVE-2021-21280 has a CVSS v3 base score of 8.6 (HIGH).

What is the EPSS score for CVE-2021-21280?

CVE-2021-21280 has an EPSS score of 1.06% (61th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-21280?

Upgrade contiki-ng to 4.6 or later.

CVE & CISA-KEV Catalog

CVE-2021-21280

HIGH

8.6

CVSS v3

NVD

Description

Contiki-NG is an open-source, cross-platform operating system for internet of things devices. It is possible to cause an out-of-bounds write in versions of Contiki-NG prior to 4.6 when transmitting a 6LoWPAN packet with a chain of extension headers. Unfortunately, the written header is not checked to be within the available space, thereby making it possible to write outside the buffer. The problem has been patched in Contiki-NG 4.6. Users can apply the patch for this vulnerability out-of-band as a workaround.

CWE-787Out-of-bounds Write

How to fix

Remediation Available

contiki-ngNVD

Affected:< 4.6Fixed in:4.6CVE-2021-21280derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Exploit Intelligence

1.06%probability of exploitation in 30 days

61stpercentile

Moderate risk: more likely to be exploited than 61% of all known CVEs.

References

Patch2

Related Vulnerabilities

Other CWE-787 (Out-of-bounds Write) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-22457	Critical	9.0	100%	KEV + Ransom	Fix
CVE-2025-0282	Critical	9.0	100%	KEV + Ransom	-
CVE-2015-3113	Critical	9.8	100%	KEV	Fix
CVE-2021-20038	Critical	9.8	100%	KEV + Ransom	-
CVE-2023-4863	High	8.8	100%	KEV	Fix
CVE-2020-16040	Medium	6.5	100%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.