/ 
CGI-Session-4.41 UNAUTHORIZED RELEASE
/ CGI::Session::ID::incr
Security Advisories (1)
CVE-2026-56016 (2026-07-01)

CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources. The generate_id method builds the session id from a MD5 digest of the process id, the epoch time, and the built-in rand() function. All three are predictable, low-entropy sources: the PID is drawn from a small range, the epoch time can be guessed or read from the HTTP Date header, and Perl's rand() is unsuitable for security purposes because it is predictable and reversible. An attacker who predicts a session id can impersonate the corresponding session and bypass authentication.

NAME

CGI::Session::ID::incr - CGI::Session ID driver

SYNOPSIS

use CGI::Session;
$session = new CGI::Session("id:Incr", undef, {
                            Directory   => '/tmp',
                            IDFile      => '/tmp/cgisession.id',
                            IDInit      => 1000,
                            IDIncr      => 2 });

DESCRIPTION

CGI::Session::ID::incr is to generate auto incrementing Session IDs. Compare it with CGI::Session::ID::md5, where session ids are truly random 32 character long strings. CGI::Session::ID::incr expects the following arguments passed to CGI::Session->new() as the third argument.

IDFile

Location where auto incremented IDs are stored. This attribute is required.

IDInit

Initial value of the ID if it's the first ID to be generated. For example, if you want the ID numbers to start with 1000 as opposed to 0, that's where you should set your value. Default is 0.

IDIncr

How many digits each number should increment by. For example, if you want the first generated id to start with 1000, and each subsequent id to increment by 10, set IDIncr to 10 and IDInit to 1000. Default is 1.

LICENSING

For support and licensing information see CGI::Session