CVE-2025-40926

CRITICAL 9.8

Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely

CVSS Score

9.8

EPSS Score

0.1%

EPSS Percentile

22th

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.

CWE	CWE-340 CWE-338
Vendor	kazeburo
Product	plack::middleware::session::simple
Published	Mar 5, 2026
Last Updated	Apr 21, 2026

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Affected Versions

KAZEBURO / Plack::Middleware::Session::Simple

0 < 0.05

References

NVD ↗ CVE.org ↗ EPSS Data ↗

metacpan.org: https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.04/source/lib/Plack/Middleware/Session/Simple.pm#L43 github.com: https://github.com/kazeburo/Plack-Middleware-Session-Simple/pull/4 github.com: https://github.com/kazeburo/Plack-Middleware-Session-Simple/commit/760bb358b8f53e52cf415888a4ac858fd99bb24e.patch cve.org: https://www.cve.org/CVERecord?id=CVE-2025-40923 security.metacpan.org: https://security.metacpan.org/docs/guides/random-data-for-security.html metacpan.org: https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.05/changes