CGI versions before 5.00 for Perl allow an infinite loop on a short request body when $DISABLE_UPLOADS is set.

When $CGI::PUTDATA_UPLOAD or an upload hook is set, read_postdata_putdata takes a request body that is not a form submission. With $CGI::DISABLE_UPLOADS set, it discards the body by reading until Content-Length bytes have arrived. Once a body shorter than its Content-Length runs out, every read returns 0, so the loop never ends.

A client can keep a server process spinning with one such request.

CGI versions before 5.00 for Perl allow an infinite loop on a short request body when $DISABLE_UPLOADS is set.

When $CGI::PUTDATA_UPLOAD or an upload hook is set, read_postdata_putdata takes a request body that is not a form submission. With $CGI::DISABLE_UPLOADS set, it discards the body by reading until Content-Length bytes have arrived. Once a body shorter than its Content-Length runs out, every read returns 0, so the loop never ends.

A client can keep a server process spinning with one such request.

perl-CGI-5.20.0-1.1 on GA media

Affected: Ubuntu:16.04:LTS: libcgi-pm-perl, Ubuntu:18.04:LTS: libcgi-pm-perl, Ubuntu:20.04:LTS: libcgi-pm-perl, Ubuntu:22.04:LTS: libcgi-pm-perl, Ubuntu:24.04:LTS: libcgi-pm-perl, Ubuntu:26.10: libcgi-pm-perl, Ubuntu:26.04:LTS: libcgi-pm-perl

CGI versions before 5.00 for Perl allow an infinite loop on a short request body when $DISABLE_UPLOADS is set. When $CGI::PUTDATA_UPLOAD or an upload hook is set, read_postdata_putdata takes a request body that is not a form submission. With $CGI::DISABLE_UPLOADS set, it discards the body by reading until Content-Length bytes have arrived. Once a body shorter than its Content-Length runs out, every read returns 0, so the loop never ends. A client can keep a server process spinning with one such request.