CVE-2025-40923: Plack-Middleware-Session before version 0.35 for Perl generates session ids insecurely
Source GCVE Database
Not known to be exploited · CVSS 7.3 High.
Data as of 4 Nov 2026, 17:54 UTC
Thin evidence
One scorer or none| CISA-ADP | CVSS 3.1 | 7.3 |
|---|
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:LExploitation evidence
Disclosed: evidence found.
CVE published 16 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.
What to do
AI-suggested
Upgrade Plack-Middleware-Session to version 0.35 or later, where the session ID generation has been improved to use a cryptographically secure method. Avoid relying on the built-in rand function for cryptographic purposes.
Description
Plack-Middleware-Session versions prior to 0.35 for Perl generate session IDs using an insecure method. The default session ID generator uses a SHA-1 hash seeded with the built-in rand function, epoch time, and process ID (PID). Because the PID is from a small range and the epoch time may be guessable or leaked, the session IDs are predictable. This vulnerability could allow attackers to guess session IDs and gain unauthorized access.
References
- nvd.nist.gov/vuln/detail/CVE-2025-40923 (opens in a new tab)
- github.com/plack/Plack-Middleware-Session/pull/52 (opens in a new tab)
- github.com/plack/Plack-Middleware-Session/commit/1fbfbb355e34e7f4b3906f66cf958cedadd2b9be.patch (opens in a new tab)
- metacpan.org/release/MIYAGAWA/Plack-Middleware-Session-0.34/source/lib/Plack/Session/State.pm (opens in a new tab)
- security.metacpan.org/docs/guides/random-data-for-security.html (opens in a new tab)
- openwall.com/lists/oss-security/2025/07/16/4 (opens in a new tab)