CVE-2026-92389 – libcurl’s TFTP state machine fails to validate state transitions against the requested tra

libcurl’s TFTP state machine fails to validate state transitions against the
requested transfer direction, accepting opening server responses for both
reads and writes interchangeably. A malicious TFTP server can respond to a
download request in a way that forces the client into transmit mode, prompting
libcurl to consume and transmit data from the handle’s persistent
`CURLOPT_READDATA` pointer – including data remaining from unrelated prior
operations, such as an HTTP POST request executed on a reused handle.