CGI versions before 5.00 for Perl allow denial of service via submitted values used as a regex for optgroup selection in scrolling_list.

When rendering option groups, scrolling_list marks the selected options by interpolating each selected value, by default taken from the request parameters, unescaped into a substitution pattern.

A client can make the request die with an invalid pattern, or tie up the process with one that backtracks heavily.

CGI versions before 5.00 for Perl allow denial of service via submitted values used as a regex for optgroup selection in scrolling_list.

When rendering option groups, scrolling_list marks the selected options by interpolating each selected value, by default taken from the request parameters, unescaped into a substitution pattern.

A client can make the request die with an invalid pattern, or tie up the process with one that backtracks heavily.

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 denial of service via submitted values used as a regex for optgroup selection in scrolling_list. When rendering option groups, scrolling_list marks the selected options by interpolating each selected value, by default taken from the request parameters, unescaped into a substitution pattern. A client can make the request die with an invalid pattern, or tie up the process with one that backtracks heavily.