CVE-2026-40613: Coturn Project Coturn

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

Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.10.0, the STUN/TURN attribute parsing functions in coturn perform unsafe pointer casts from uint8_t * to uint16_t * without alignment checks. When processing a crafted STUN message with odd-aligned attribute boundaries, this results in misaligned memory reads at ns_turn_msg.c. On ARM64 architectures (AArch64) with strict alignment enforcement, this causes a SIGBUS signal that immediately kills the turnserver process. An unauthenticated remote attacker can crash any ARM64 coturn deployment by sending a single crafted UDP packet. This vulnerability is fixed in 4.10.0.

Affected products

• Coturn Project Coturn: before 4.10.0 (fixed in 4.10.0)

Published 2026-04-21. Last modified 2026-06-17.