# CVE-2025-40923: libplack-middleware-session-perl: Plack-Middleware-Session before version 0.35 for Perl generates session ids insecurely

CVE-2025-40923 is fixed in libplack-middleware-session-perl on 1 platform by DEBIAN-CVE-2025-40923 (version 0.36-1), released July 16, 2025. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2025-40923
- Priority: High
- CVSS: 7.3 (high)
- EPSS: 0.0039
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 16, 2025

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libplack-middleware-session-perl Debian 14 | 0.36-1 | [DEBIAN-CVE-2025-40923](https://patchblox.com/security/data/fix/linux/debian-cve-2025-40923.md) | Jul 16, 2025 |

---

Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.