AnyIO vulnerabilities

In AnyIO 4.14.0, open_process() forwards the group argument to the backend instead of extra_groups, despite accepting the extra_groups parameter. A call with extra_groups=[] to clear inherited supplementary groups can launch a child process that retains the parent's groups, weakening a privilege-dropping boundary. This affects POSIX applications using AnyIO subprocess helpers and is fixed in version 4.14.2.

AnyIO's TLS connections to internationalized (non-ASCII) domain names may be vulnerable if the connection is hijacked and redirected to a malicious server, potentially allowing man-in-the-middle attacks.

In AnyIO prior to 4.14.2, process-pool workers were started with stderr connected to a pipe the parent never drained. Worker code writing enough data to sys.stderr could fill the pipe and block before returning the response, causing the awaiting process-pool call to remain blocked indefinitely.