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Coturn Misaligned Pointer Cast in STUN Attribute Parsing Causes a SIGBUS Crash on ARM64, Triggerable by a Single Unauthenticated STUN Message

Last refreshed2026-09-30

Status: UPDATED  |  Advisory ID: CVE-2026-40613

Key Details

CVECVE-2026-40613
CVSS Score / Version7.5 (High) / CVSS v3.1
Updated2026-06-17
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Proseattack vector is network; attack complexity is low; privileges required is none; user interaction is none; scope is unchanged; confidentiality impact is none; integrity impact is none; availability impact is high.
Affected productscoturn_project coturn
Classified asCWE-704 (Incorrect Type Conversion or Cast)

Affected Products, Subsystems & Sectors

VendorProductAffected VersionsPatch Status
coturn_projectcoturn
SubsystemsGeneral OT
SectorsMultiple

What to Know

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. (NVD)

What to Do

Monitor coturn_project's web page for any future patch releases. See vendor advisory link below.

References

SourceReference
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-40613
CVEhttps://www.cve.org/CVERecord?id=CVE-2026-40613
Vendor advisoryhttps://github.com/coturn/coturn/security/advisories/GHSA-j662-9wcj-mf36