Vulnerability Details 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 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.006
EPSS Ranking 46.5%
CVSS Severity
CVSS v3 Score 9.8
References
Products affected by CVE-2026-5067
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cpe:2.3:o:zephyrproject:zephyr:3.7.0
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cpe:2.3:o:zephyrproject:zephyr:3.7.1
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cpe:2.3:o:zephyrproject:zephyr:3.7.2
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cpe:2.3:o:zephyrproject:zephyr:4.0.0
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cpe:2.3:o:zephyrproject:zephyr:4.1.0
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cpe:2.3:o:zephyrproject:zephyr:4.2.0
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cpe:2.3:o:zephyrproject:zephyr:4.2.1
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cpe:2.3:o:zephyrproject:zephyr:4.3.0