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.

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Advisories

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Fixes

Solution

Upgrade to CGI::Session 4.49 or later, which generates session ids from Crypt::SysRandom.


Workaround

No workaround given by the vendor.

History

Thu, 02 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-331
References
Metrics threat_severity

None

threat_severity

Important


Wed, 01 Jul 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 01 Jul 2026 08:15:00 +0000

Type Values Removed Values Added
Description 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.
Title CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources
Weaknesses CWE-338
CWE-340
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: CPANSec

Published:

Updated: 2026-07-01T17:36:49.480Z

Reserved: 2026-06-18T11:27:09.117Z

Link: CVE-2026-56016

cve-icon Vulnrichment

Updated: 2026-07-01T17:36:49.480Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Important

Publid Date: 2026-07-01T06:46:23Z

Links: CVE-2026-56016 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-02T08:15:04Z

Weaknesses