CVE-2025-40926 | Plack::Middleware::Session::Simple versions before 0.05 for … | CVSS 9.8 CRITICAL

Description

Plack::Middleware::Session::Simple versions before 0.05 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. Predictable session ids could allow an attacker to gain access to systems. Plack::Middleware::Session::Simple is intended to be compatible with Plack::Middleware::Session, which had a similar security issue CVE-2025-40923.

Metadata

CVE ID: CVE-2025-40926
State: PUBLISHED
Assigner: CPANSec
Reserved: 2025-04-16 09:05 UTC
Published: 2026-03-05 01:24 UTC
Last updated: 2026-04-21 02:42 UTC
Primary CWE: CWE-340
CWE-340 Generation of Predictable Numbers or Identifiers
Vendor / Product: KAZEBURO / Plack::Middleware::Session::Simple
Sources: cve.org · NVD

Severity & Metrics

9.8 CRITICAL CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

SSVC — CISA Coordinator

Exploitation: none
Automatable: yes
Tech. Impact: total

Affected products (1)

Vendor	Product	Platform	Versions
KAZEBURO	Plack::Middleware::Session::Simple	—	0 < 0.05

Weakness (CWE)

CWE	Source	Description
CWE-338	cna	CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator
CWE-340	cna	CWE-340 Generation of Predictable Numbers or Identifiers

CVSS scores (1)

Score	Severity	Version	Source	Vector
9.8	CRITICAL	3.1	adp	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References (6)