How severe is CVE-2021-42142?

CVE-2021-42142 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-42142 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-2021-42142?

CVE-2021-42142 affects Contiki-ng Tinydtls. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42142?

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

Does CVE-2021-42142 have an EU (EUVD) identifier?

Yes. CVE-2021-42142 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-29125.

When was CVE-2021-42142 published?

CVE-2021-42142 was published on 2024-01-23 and last updated on 2026-06-17.

CVE-2021-42142

CVE-2021-42142 is a critical-severity vulnerability in Contiki-ng Tinydtls with a CVSS 3.x base score of 9.8. 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-755.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2021-29125
Weakness: CWE-755
Affected product: Contiki-ng Tinydtls
Published: 2024-01-23
Last modified: 2026-06-17

Description

An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. DTLS servers mishandle the early use of a large epoch number. This vulnerability allows remote attackers to cause a denial of service and false-positive packet drops.

Frequently asked questions

What is CVE-2021-42142?: An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. DTLS servers mishandle the early use of a large epoch number. This vulnerability allows remote attackers to cause a denial of service and false-positive packet drops.
How severe is CVE-2021-42142?: CVE-2021-42142 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-42142 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-2021-42142?: CVE-2021-42142 affects Contiki-ng Tinydtls. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42142?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2021-42142 have an EU (EUVD) identifier?: Yes. CVE-2021-42142 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-29125.
When was CVE-2021-42142 published?: CVE-2021-42142 was published on 2024-01-23 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:contiki-ng:tinydtls:*:*:*:*:*:*:*:*

More vulnerabilities in Contiki-ng Tinydtls

CVE-2021-42141 — Critical (CVSS 9.8): An issue was discovered in Contiki-NG tinyDTLS through 2018-08-30. One incorrect handshake could complete with…
CVE-2021-42147 — Critical (CVSS 9.1): Buffer over-read vulnerability in the dtls_sha256_update function in Contiki-NG tinyDTLS through master branch 53a0d97…
CVE-2021-42143 — Critical (CVSS 9.1): An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop bug exists during the…
CVE-2021-42146 — High (CVSS 7.5): An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. DTLS servers allow remote attackers to…
CVE-2021-42145 — High (CVSS 7.5): An assertion failure discovered in in check_certificate_request() in Contiki-NG tinyDTLS through master branch 53a0d97…

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CVE-2021-42141 — Critical (CVSS 9.8): An issue was discovered in Contiki-NG tinyDTLS through 2018-08-30. One incorrect handshake could complete with…
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