CVE-2026-5067 Out-of-bounds read/write in HTTP WebSocket upgrade via non-null-terminated Sec-WebSocket-Key
Remote attackers can cause memory corruption and potential code execution in Zephyr's HTTP server via a crafted WebSocket header when WebSocket support is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-5067?
CVE-2026-5067 is a critical memory corruption vulnerability in Zephyrproject Zephyr, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-5067?
It affects 1 product.
Products include Zephyrproject Zephyr.
How do I fix CVE-2026-5067?
No fix has been published for CVE-2026-5067 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-5067 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5067 exists.
Other vulnerabilities in Zephyrproject Zephyr
- CVE-2022-3806 Bluetooth HCI Error Handling Double Free
- CVE-2017-14199 Memory corruption in getaddrinfo
- CVE-2018-1000800 Null dereference in n/a
- CVE-2021-3329 DOS: Incorrect handling of the initial HCI ACL_MTU handshake packet leads to crash of bluetooth host layer
- CVE-2023-0397 DoS: Invalid Initialization in le_read_buffer_size_complete
Sources
Also known as GHSA-wgr4-9pwq-94vj.