How severe is CVE-2021-42143?

CVE-2021-42143 has a CVSS 3.x base score of 9.1, 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 none, and availability high.

Is CVE-2021-42143 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42143?

CVE-2021-42143 affects Contiki-ng Tinydtls. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42143?

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-2021-42143 have an EU (EUVD) identifier?

Yes. CVE-2021-42143 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-29126.

When was CVE-2021-42143 published?

CVE-2021-42143 was published on 2024-01-24 and last updated on 2026-06-17.

CVE-2021-42143

CVE-2021-42143 is a critical-severity vulnerability in Contiki-ng Tinydtls with a CVSS 3.x base score of 9.1. 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: Critical (CVSS 3.x base score 9.1)
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2021-29126
Weakness: CWE-835
Affected product: Contiki-ng Tinydtls
Published: 2024-01-24
Last modified: 2026-06-17

Description

An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop bug exists during the handling of a ClientHello handshake message. This bug allows remote attackers to cause a denial of service by sending a malformed ClientHello handshake message with an odd length of cipher suites, which triggers an infinite loop (consuming all resources) and a buffer over-read that can disclose sensitive information.

Frequently asked questions

What is CVE-2021-42143?: An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop bug exists during the handling of a ClientHello handshake message. This bug allows remote attackers to cause a denial of service by sending a malformed ClientHello handshake message with an odd length of cipher suites, which triggers an infinite loop (consuming all resources) and a buffer over-read that can disclose sensitive information.
How severe is CVE-2021-42143?: CVE-2021-42143 has a CVSS 3.x base score of 9.1, 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 none, and availability high.
Is CVE-2021-42143 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42143?: CVE-2021-42143 affects Contiki-ng Tinydtls. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42143?: 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-2021-42143 have an EU (EUVD) identifier?: Yes. CVE-2021-42143 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-29126.
When was CVE-2021-42143 published?: CVE-2021-42143 was published on 2024-01-24 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-2021-42142 — Critical (CVSS 9.8): An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. DTLS servers mishandle the early use of a…
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-2021-42146 — 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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