CVE-2020-12457: wolfSSL

High severity, CVSS 7.5. EPSS: 1.5% chance of exploitation in the next 30 days.

An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.

Affected products

• wolfSSL wolfSSL: before 4.5.0 (fixed in 4.5.0)

Published 2020-08-21. Last modified 2026-06-17.