CVE-2025-40926
Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely
- State
- Published
- Severity
- 9.8 Critical
- Published
- Mar 5, 2026
- Updated
- Apr 21, 2026
- Reserved
- Apr 16, 2025
Description
Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely.
The default session id generator returns a SHA-1 hash seeded with the built-in rand function, the epoch time, and the PID. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage.
Predictable session ids could allow an attacker to gain access to systems.
Plack::Middleware::Session::Simple is intended to be compatible with Plack::Middleware::Session, which had a similar security issue CVE-2025-40923.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | CISA-ADP |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
Plack::Middleware::Session::SimpleKAZEBURO |
|
References
- https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.04/source/lib/Plack/Middleware/Session/Simple.pm#L43
- https://github.com/kazeburo/Plack-Middleware-Session-Simple/pull/4issue-tracking
- https://github.com/kazeburo/Plack-Middleware-Session-Simple/commit/760bb358b8f53e52cf415888a4ac858fd99bb24e.patchpatch
- https://www.cve.org/CVERecord?id=CVE-2025-40923vendor-advisoryrelatedvdb-entry
- https://security.metacpan.org/docs/guides/random-data-for-security.htmltechnical-description
- https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.05/changesrelease-notes
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