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Vulnerability · Published Jul 16, 2025 · Assigned by CPANSec

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

High 7.3

In plain English

A high-severity security flaw in Plack::Middleware::Session from MIYAGAWA. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.3High
Exploit odds (30 days)0.4%top 66.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12libplack-middleware-session-perlno fix listedDEBIAN-CVE-2025-40923
Debian:13libplack-middleware-session-perlno fix listedDEBIAN-CVE-2025-40923
Debian:14libplack-middleware-session-perl0.36-1DEBIAN-CVE-2025-40923
Ubuntu:22.04:LTSlibplack-middleware-session-perlno fix listedUBUNTU-CVE-2025-40923
Ubuntu:24.04:LTSlibplack-middleware-session-perlno fix listedUBUNTU-CVE-2025-40923
Ubuntu:25.10libplack-middleware-session-perlno fix listedUBUNTU-CVE-2025-40923

Affected products (as reported)

VendorProductVersions
MIYAGAWA Plack::Middleware::Session 0.01 – before 0.35

Weakness: CWE-340, CWE-338 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

References