CVE-2023-23759: Facebook Fizz

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

There is a vulnerability in the fizz library prior to v2023.01.30.00 where a CHECK failure can be triggered remotely. This behavior requires the client supported cipher advertisement changing between the original ClientHello and the second ClientHello, crashing the process (impact is limited to denial of service).

Affected products

• Facebook Fizz: before 2023.01.30.00 (fixed in 2023.01.30.00)

Published 2023-05-18. Last modified 2026-06-17.