CVE-2025-40923
Plack-Middleware-Session before version 0.35 for Perl generates session ids insecurely.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.33%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Plack-Middleware-Session before version 0.35 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. Predicable session ids could allow an attacker to gain access to systems.
- CVSS 3.1
- 7.3 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- EPSS
- 0.33% probability · 26th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-338, CWE-340
- Source
- 9b29abf9-4ab0-4765-b253-1875cd9b441e
References
- https://github.com/plack/Plack-Middleware-Session/commit/1fbfbb355e34e7f4b3906f66cf958cedadd2b9be.patch
- https://github.com/plack/Plack-Middleware-Session/pull/52
- https://metacpan.org/release/MIYAGAWA/Plack-Middleware-Session-0.34/source/lib/Plack/Session/State.pm#L22
- https://security.metacpan.org/docs/guides/random-data-for-security.html
- http://www.openwall.com/lists/oss-security/2025/07/16/4
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.