# CVE-2026-5067

## Summary

- **CVE ID:** CVE-2026-5067
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-170, CWE-787
- **Published:** Jun 9, 2026
- **Last Modified:** Jun 9, 2026

## Description

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 bounded copy that does not guarantee NUL termination when the input length reaches the buffer size. During upgrade handling the buffer is copied to a local stack buffer and passed to strlen(); if no NUL exists in-bounds, strlen() reads beyond the stack buffer and subsequent concatenation with the WebSocket magic string can write out of bounds. This leads to out-of-bounds read and write on stack memory, resulting in crash (denial of service) and potentially code execution. The path is reachable when CONFIG_HTTP_SERVER_WEBSOCKET is enabled.

## Affected Products

- zephyrproject-rtos — Zephyr (3.7.0)

## References

- [CNA](https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-wgr4-9pwq-94vj)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.64%
- **EPSS Percentile:** 48.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._