CVE-2026-40613

Coturn: Misaligned Memory Access in coturn STUN Attribute Parser (Remote DoS on ARM64)

Published Apr 21, 2026 CVSS 3.1 · 7.5 High EPSS 1.1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Coturn Project
Coturn Project coturn
CPEs cpe:2.3:a:coturn_project:coturn:*:*:*:*:*:*:*:*
Vendors & Products Coturn Project
Coturn Project coturn
Type Values Removed Values Added
First Time appeared Coturn
Coturn coturn
Vendors & Products Coturn
Coturn coturn
Type Values Removed Values Added
Description 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.
Title Coturn: Misaligned Memory Access in coturn STUN Attribute Parser (Remote DoS on ARM64)
Weaknesses CWE-704
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Apr 21, 2026, 8:36 PM
Reserved
Apr 14, 2026, 2:07 PM
Status
Analyzed
Published
Apr 21, 2026, 7:16 PM
Modified
Nov 11, 2026, 11:10 PM