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VulnerabilityPublished Updated

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

Source GCVE Database

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Authoritative record:CVE-2025-40923· High 7.3

Not known to be exploited · CVSS 7.3 High.

Data as of 4 Nov 2026, 17:54 UTC

CVSS 3.1 base score
7.3High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.17.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 16 Jul 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

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