MicroPython modselect.c poll_set_add_fd use after free

A vulnerability, which was classified as critical, has been found in MicroPython 1.21.0/1.22.0-preview. Affected by this issue is the function poll_set_add_fd of the file extmod/modselect.c. The manipulation leads to use after free. The exploit has been disclosed to the public and may be used. The patch is identified as 8b24aa36ba978eafc6114b6798b47b7bfecdca26. It is recommended to apply a patch to fix this issue. VDB-249158 is the identifier assigned to this vulnerability.