CVE-2026-10655— Use-after-free race in SNTP async client when closing the socket while the socket service is still polling it

Use-after-free race in SNTP async client when closing the socket while the socket service is still polling it

The asynchronous SNTP client in Zephyr (subsys/net/lib/sntp/sntp.c, sntp_close_async) closed the UDP socket file descriptor directly from the calling thread immediately after detaching it from the network socket service, without synchronizing with the socket-service poll thread. The socket service thread polls each socket via zvfs_poll, which (in zsock_poll_prepare_ctx) registers a k_poll_event pointing into the socket's net_context (&ctx->recv_q) and then blocks in k_poll without holding a reference or lock. net_context objects are allocated from a fixed pool (contexts[CONFIG_NET_MAX_CONTEXTS]) and reused after close. When sntp_close_async is invoked from a different thread than the poll thread (in the in-tree consumer subsys/net/lib/config/init_clock_sntp.c, the SNTP timeout handler runs on the system workqueue while the socket service thread is blocked in poll on the same fd), the close frees and may reuse the net_context while the poll thread still has a poller node linked into the freed object, resulting in a use-after-free / object confusion of kernel poll structures. The SNTP timeout path is the normal no-response failure mode, so a network peer or off-path attacker who drops or delays the SNTP/NTP response can drive the racing close repeatedly (and periodically with NET_CONFIG_SNTP_INIT_RESYNC). The most likely consequence is a crash of the networking thread (denial of service), with potential memory corruption when the freed context slot is reallocated. The fix defers the close to the socket service thread itself via net_socket_service_close (NET_SOCKET_SERVICE_CLOSE_SOCKETS), so the same thread that polls performs the close, eliminating the race. Affected releases: v4.2.0 through v4.4.0.

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

释放后使用

Zephyr 资源管理错误漏洞

Zephyr是Zephyr组织开源的一个可扩展的实时操作系统 (RTOS)。 Zephyr 4.2.0版本至4.4.0版本存在资源管理错误漏洞，该漏洞源于SNTP客户端在关闭UDP套接字文件描述符时未与套接字服务轮询线程同步，导致释放后重用，可能造成内核轮询结构对象混淆，攻击者通过丢弃或延迟SNTP/NTP响应可重复触发竞争，最可能导致网络线程崩溃（拒绝服务）。

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