Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-07-01T06:46:23 perl-CGI-Session: perl-CGI-Session: Authentication bypass via predictable session IDs 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N CWE-331

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.

A flaw was found in perl-CGI-Session. This vulnerability allows a remote attacker to predict session identifiers due to the use of low-entropy sources in the `generate_id` method. By predicting a session identifier, an attacker can impersonate a user's session, leading to a bypass of authentication mechanisms and potential unauthorized access to sensitive information or functionality.

This Important flaw in perl-CGI-Session allows a remote attacker to bypass authentication by predicting session identifiers. The `CGI::Session::ID::md5` module generates session IDs using low-entropy sources, including process ID, epoch time, and a predictable random number generator. This predictability enables an attacker to impersonate a user's session, potentially leading to unauthorized access in web applications utilizing this module for session management. Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Red Hat Enterprise Linux 6 Affected perl-CGI-Session Red Hat Enterprise Linux 7 Affected perl-CGI-Session https://www.cve.org/CVERecord?id=CVE-2026-56016 https://nvd.nist.gov/vuln/detail/CVE-2026-56016 https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/changes https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/source/lib/CGI/Session/ID/md5.pm