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CVE-2025-40926

CRITICAL

9.8

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.

CVE Details

CVSS v3.1 Score9.8

SeverityCRITICAL

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionNONE

Published3/5/2026

Last Modified3/12/2026

Sourcenvd

Honeypot Sightings0

Affected Products

kazeburo:plack\

Weaknesses (CWE)

CWE-338CWE-340

References

https://github.com/kazeburo/Plack-Middleware-Session-Simple/commit/760bb358b8f53e52cf415888a4ac858fd99bb24e.patch(9b29abf9-4ab0-4765-b253-1875cd9b441e)

https://github.com/kazeburo/Plack-Middleware-Session-Simple/pull/4(9b29abf9-4ab0-4765-b253-1875cd9b441e)

https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.04/source/lib/Plack/Middleware/Session/Simple.pm#L43(9b29abf9-4ab0-4765-b253-1875cd9b441e)

https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.05/changes(9b29abf9-4ab0-4765-b253-1875cd9b441e)

https://security.metacpan.org/docs/guides/random-data-for-security.html(9b29abf9-4ab0-4765-b253-1875cd9b441e)

https://www.cve.org/CVERecord?id=CVE-2025-40923(9b29abf9-4ab0-4765-b253-1875cd9b441e)

IOC Correlations

No correlations recorded

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