Vulnerability 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.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/changes
- https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/source/lib/CGI/Session/ID
- http://www.openwall.com/lists/oss-security/2026/07/01/6
FAQ
What is CVE-2026-56016?
CVE-2026-56016 is a vulnerability with a CVSS score of 5.9 (MEDIUM). 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 ep...
How severe is CVE-2026-56016?
CVE-2026-56016 has been rated MEDIUM with a CVSS base score of 5.9/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-56016?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.