CVE-2021-34433: Eclipse Californium

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

In Eclipse Californium version 2.0.0 to 2.6.4 and 3.0.0-M1 to 3.0.0-M3, the certificate based (x509 and RPK) DTLS handshakes accidentally succeeds without verifying the server side's signature on the client side, if that signature is not included in the server's ServerKeyExchange.

Affected products

• Eclipse Californium: from 2.0.0, before 2.6.5 (fixed in 2.6.5); version 3.0.0 only

Published 2021-08-20. Last modified 2026-06-17.