CVE-2026-5067Public exploitNetwork attack vector

Memory corruption via unterminated WebSocket key

Published Jun 9, 2026 · Updated Jun 9, 2026

Memory corruption in Zephyr RTOS 3.7.0 through 4.3.0 allows remote attackers to crash devices or execute code via WebSocket upgrades. The HTTP/1 parser uses strncpy to copy Sec-WebSocket-Key into a fixed buffer without guaranteed NUL termination, then upgrade handling passes a stack copy to strlen and appends a magic string out of bounds. Exploitation requires CONFIG_HTTP_SERVER_WEBSOCKET; a crafted unauthenticated request causes stack reads and writes, with a crash demonstrated and code execution dependent on target layout.

CVSS severity9.8
Critical
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Memory corruption in Zephyr RTOS 3.7.0 through 4.3.0 allows remote attackers to crash devices or execute code via WebSocket upgrades. The HTTP/1 parser uses strncpy to copy Sec-WebSocket-Key into a fixed buffer without guaranteed NUL termination, then upgrade handling passes a stack copy to strlen and appends a magic string out of bounds. Exploitation requires CONFIG_HTTP_SERVER_WEBSOCKET; a crafted unauthenticated request causes stack reads and writes, with a crash demonstrated and code execution dependent on target layout.

The record

CVE
CVE-2026-5067
Published
Jun 9, 2026
Updated
Jun 9, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-170, CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.7.0 <=4.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=3.7.0 <=4.3.0

Published CVSS scores

9.8Zephyr ProjectCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-170Improper Null Termination
CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo