# CVE-2025-40931

## Summary

- **CVE ID:** CVE-2025-40931
- **Severity:** CRITICAL
- **CVSS Score:** 9.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N)
- **CWE:** CWE-340, CWE-338
- **Published:** Mar 5, 2026
- **Last Modified:** Apr 21, 2026

## Description

Apache::Session::Generate::MD5 versions through 1.94 for Perl create insecure session id.

Apache::Session::Generate::MD5 generates session ids insecurely. The default session id generator returns a MD5 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.

## Affected Products

- CHORNY — Apache::Session::Generate::MD5 (0)

## References

- [CNA](https://metacpan.org/dist/Apache-Session/source/lib/Apache/Session/Generate/MD5.pm#L27)
- [CNA](https://security.metacpan.org/docs/guides/random-data-for-security.html)
- [CNA](https://github.com/chorny/Apache-Session/issues/4)
- [CNA](https://rt.cpan.org/Ticket/Display.html?id=173631)
- [CVE](http://www.openwall.com/lists/oss-security/2026/03/05/3)
- [CNA](https://www.openwall.com/lists/oss-security/2019/06/15/1)
- [CNA](https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=930659)
- [CNA](https://salsa.debian.org/perl-team/modules/packages/libapache-session-perl/-/commit/bdabd71c2f91b18526e31a9dc52b4c17b3d246b7#898a4b8b00022df1b8689910b67707f3e738d180)
- [CNA](https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/work_items/1633)
- [CNA](https://metacpan.org/pod/Apache::Session::Generate::Random)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.58%
- **EPSS Percentile:** 45.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._