CVE-2026-10849— Heap out-of-bounds write in Zephyr hawkBit OTA client when terminating server response body

Heap out-of-bounds write in Zephyr hawkBit OTA client when terminating server response body

The hawkBit device management client in subsys/mgmt/hawkbit accumulates the body of an HTTP response from the update server into a heap buffer in response_json_cb() (subsys/mgmt/hawkbit/hawkbit.c). The buffer is sized to hold the received body bytes but reserves no space for a terminating NUL. When the full response has arrived, the code writes response_data[downloaded_size] = '\0' — and whenever the accumulated body length equals the allocation, that terminator lands one byte past the end of the heap object (a heap-based out-of-bounds write, CWE-122 / CWE-787). The body length and fragmentation are taken directly from the parsed HTTP response (rsp->body_frag_start / rsp->body_frag_len) and are fully controlled by the remote hawkBit server, which chooses its own response length. The precise trigger depends on how the buffer grows, and both forms are remotely reachable. Since v4.0.0 the reallocation is sized to exactly downloaded_size + body_len, so any response body larger than the 1100-byte initial buffer makes the out-of-bounds write deterministic; such response sizes are normal for hawkBit deployment metadata. Before v4.0.0 the buffer grew by doubling and the growth check ((downloaded_size + body_len) > response_buffer_size) is false at equality, so a response body whose length is exactly the current allocation — 1100 bytes with the default initial buffer — skips the reallocation entirely and writes the terminator at response_data[1100] of an 1100-byte object. The HTTP length-mismatch check does not catch this, because the declared and received lengths genuinely agree. Either form is reachable by a malicious, compromised, or man-in-the-middle update server (TLS is optional and, when enabled, does not protect against a hostile server), with no authentication of response content and no client-side length cap protecting the write. The out-of-bounds write is a fixed single NUL byte immediately following the allocation, corrupting adjacent allocator metadata or the next allocation. The practical impact is heap corruption leading to denial of service (fault on a subsequent allocation or free), with the bounded, allocator-dependent possibility of further corruption. The fix sizes the buffer to the body length plus one and copies with memcpy, ensuring the terminator always lands within the allocation.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

堆缓冲区溢出

zephyrproject zephyr 缓冲区错误漏洞

zephyrproject zephyr是zephyrproject组织开源的一款实时操作系统内核。 zephyrproject zephyr 2.4.0版本至4.5.0之前版本存在缓冲区错误漏洞，该漏洞源于hawkBit设备管理客户端在response_json_cb()函数中处理HTTP响应时，缓冲区未预留终止NUL空间，导致堆越界写入，可能造成拒绝服务。

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