CVE-2026-40613

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

HIGH
7.5
CVSS Score
Published: April 21, 2026 at 06:00 PM UTC
Updated: June 17, 2026 at 10:45 AM UTC
1 product affected across 1 vendorCoturn

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Severity
HIGH7.5
Exploit prediction
EPSS 1%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.10.0
Affected range stops below 4.10.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

x_refsource_CONFIRMExploitVendor Advisory
Source: cverecord
https://github.com/coturn/coturn/security/advisories/GHSA-j662-9wcj-mf36

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-704

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