CVE-2025-40923
HIGHDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Exploit Intelligence
Low risk: more likely to be exploited than 25% of all known CVEs.
References
Related Vulnerabilities
Other CWE-338 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2008-0166 | High | 7.5 | 71% | - | Fix |
| CVE-2009-2367 | Critical | 9.8 | 23% | - | - |
| CVE-2024-29868 | Critical | 9.1 | 6.0% | - | - |
| CVE-2024-31497 | Medium | 5.9 | 5.8% | - | Fix |
| CVE-2021-43799 | High | 8.6 | 5.4% | - | Fix |
| CVE-2008-3280 | Medium | 5.9 | 4.0% | - | - |
Common questions
How do I fix CVE-2025-40923?
Upgrade libplack-middleware-session-perl on debian unstable to 0.36-1 or later.
Is CVE-2025-40923 being actively exploited?
Not that we know of. CVE-2025-40923 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.33% is the estimated probability that it will be exploited in the next 30 days. That is higher than 25% of all scored CVEs.
How severe is CVE-2025-40923?
CVE-2025-40923 has a CVSS v3 base score of 7.3, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2025-40923 affect?
Published advisories record a fix for libplack-middleware-session-perl (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-04.