CVE-2025-40923
What it is
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.
At a glance
- Exploitability
- Can be exploited over the network without logging in. Limited direct impact.
- Exploit odds
- 0.4% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Details
- Published
- Last modified
- Exploit probability
- 0.4% · EPSS, next 30 days
- Weakness
- CWE-338
- Record status
- Deferred
Attack profile CVSS 3.1 · 7.3
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Fix and advisories
- https://github.com/plack/Plack-Middleware-Session/commit/1fbfbb355e34e7f4b3906f66cf958cedadd2b9be.patch
- https://github.com/plack/Plack-Middleware-Session/pull/52
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