CPANSA-CGI-Session-2026-56016: CGI-Session vulnerability
| Publisher | giterlizzi | Document category | csaf_security_advisory |
|---|---|---|---|
| Initial release date | 2026-07-01T00:00:00 | Engine | CSAF Perl Toolkit 0.26 |
| Current release date | 2026-07-01T00:00:00 | Build Date | |
| Current version | 1 | Status | final |
| CVSS v3.1 Base Score | 5.9 | Severity | |
| Original language | Language | en | |
| Also referred to | |||
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.
Vulnerabilities
CVE-2026-56016
Vulnerability DescriptionCGI::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.
| Weakness | CWE-338 : Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) |
|---|
Product status
Known affected
| Product | Score | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| CGI-Session less than 4.49 |
|
Fixed
- CGI-Session greater than or equal 4.49
giterlizzi
Namespace: https://github.com/giterlizzi/
gdt@cpan.org
References
- CPANSA-CGI-Session-2026-56016 JSON self
https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa-cgi-session-2026-56016.json - https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/changes external
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 external
https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/source/lib/CGI/Session/ID/md5.pm - http://www.openwall.com/lists/oss-security/2026/07/01/6 external
http://www.openwall.com/lists/oss-security/2026/07/01/6 - CVE-2026-56016 (NVD) external
https://nvd.nist.gov/vuln/detail/CVE-2026-56016
Revision history
| Version | Date of the revision | Summary of the revision |
|---|---|---|
| 1 | Wed Jul 1 00:00:00 2026 | First release |
Sharing rules
TLP:WHITE
For the TLP version see: https://www.first.org/tlp/