CVE-2021-22901

curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability
resulting in already freed memory being used when a TLS 1.3 session ticket
arrives over a connection. A malicious server can use this in rare
unfortunate circumstances to potentially reach remote code execution in the
client. When libcurl at run-time sets up support for TLS 1.3 session
tickets on a connection using OpenSSL, it stores pointers to the transfer
in-memory object for later retrieval when a session ticket arrives. If the
connection is used by multiple transfers (like with a reused HTTP/1.1
connection or multiplexed HTTP/2 connection) that first transfer object
might be freed before the new session is established on that connection and
then the function will access a memory buffer that might be freed. When
using that memory, libcurl might even call a function pointer in the
object, making it possible for a remote code execution if the server could
somehow manage to get crafted memory content into the correct place in
memory.

Notes