9.1

CVE-2021-42143: contiki-ng tinydtls Infinite Loop

CVSS: 9.1v3.1CriticalModified
Published 24-01-2024Last modified 20-06-2025
Open JSON

Vulnerability summary

CVE-2021-42143 is a critical (CVSS 9.1) Infinite Loop vulnerability in contiki-ng tinydtls. EPSS estimates a 0.81% chance of exploitation in the next 30 days, higher than 56.4% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.81%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 24-01-2024
    PublishedVulnerability first disclosed.
  2. 20-06-2025
    Last modifiedVulnerability information updated.

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.81%

Chance of exploitation in the next 30 days

Percentile

56%

Versus all other CVEs

30-day change

0.00 pp

From 0.81% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.81%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Contiki-ng1 product

1 vendor · 1 product

References

2 links