CVE-2026-40613

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.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0019

Probability of exploitation

0.41%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-704 CWE-704

Affected Products

Vendor	Product	Versions
coturn_project	coturn	< 4.10.0

References

Advisories & Patches

https://github.com/coturn/coturn/security/advisories/GHSA-j662-9wcj-mf36 https://github.com/coturn/coturn/security/advisories/GHSA-j662-9wcj-mf36

Exploits

https://github.com/coturn/coturn/security/advisories/GHSA-j662-9wcj-mf36 https://github.com/coturn/coturn/security/advisories/GHSA-j662-9wcj-mf36

Frequently Asked Questions

What is CVE-2026-40613? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-40613? +

CVE-2026-40613 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0019, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-40613? +

CVE-2026-40613 affects products from coturn_project, specifically: coturn. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-40613? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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