What is CVE-2026-5067?

CVE-2026-5067 is a critical-severity vulnerability in Zephyrproject Zephyr, classified under Improper Null Termination. CVSS score: 9.8/10. Published 2026-06-09.

How severe is CVE-2026-5067?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Zephyrproject Zephyr

CVE-2026-5067

A remote, unauthenticated attacker can trigger memory corruption in Zephyr's HTTP server WebSocket upgrade path by sending a crafted Sec-WebSocket-Key header. The HTTP/1 header parser copies the header into a fixed-size buffer using a boun…

EPSS: 0.006 (47.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Zephyrproject Zephyr
Zephyrproject-rtos Zephyr — versions 3.7.0

Weakness classification (CWE)

CWE-170 — Improper Null Termination
CWE-787 — Out-of-bounds Write

References

vulnerabilities@zephyrproject.org (Exploit, Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-5067?: CVE-2026-5067 is a critical-severity vulnerability in Zephyrproject Zephyr, classified under Improper Null Termination. CVSS score: 9.8/10. Published 2026-06-09.
How severe is CVE-2026-5067?: Critical severity. CVSS v3 base score is 9.8 out of 10.