CVE-2026-34874: Trustedfirmware Mbed TLS

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

An issue was discovered in Mbed TLS through 3.6.5 and 4.x through 4.0.0. There is a NULL pointer dereference in distinguished name parsing that allows an attacker to write to address 0.

Affected products

• Trustedfirmware Mbed TLS: from 3.5.0, before 3.6.6 (fixed in 3.6.6); version 4.0.0 only

Published 2026-04-01. Last modified 2026-06-17.